Going to Rei was out of the question: she couldn't help and he didn't want to worry her.
Dr. Bannon needed Shinji more than he did: Tabris at least knew how to repair minor damage and not make things any worse, while the untrained human had scrambled or overwritten some very important files and actually was in immediate danger of death. Tabris was hurt, but he could wait, even if he couldn't recover completely on his own. Doing repairs to one's own base files without a spotter to keep an eye on important things the individual couldn't look at because they were what was doing the looking was certainly in the Do Not Try This At Home category, even for trained planetary humans. Tabris had learned a lot about this himself in the process of training Shinji, but he was still an angel and he still had Adam lurking in his subconscious.
Also, if Shinji saw Tabris' mind like this? Shinji was a kind person, but he was still angry over what Gendo had done to him. He didn't like to hurt others not because he was afraid of inflicting pain or them getting revenge on him, but because he knew what pain was like and didn't want to be the kind of person who hurt others, especially innocent others. Especially people that they shouldn't hurt, like their families or people who were trying to save their lives.
Hopefully, Shinji's innate compassion would make him help the other Lilim, and perhaps now that dealing with Asuka had forced him to be more open about even the feelings that led to hurting others, like anger, he might want to attempt to give the man a verbal beatdown and get him to apologize to Tabris. Personally, Tabris didn't mind. Absorbing someone's soul against their will was a sickening thing to do. It certainly wasn't anything to thank the perpetrator for, saving lives or not.
Tabris was absolutely certain he'd done the wrong thing. The trouble was that his other options had also been very bad ones. He could have killed the man, which was also a sickening thought, or refused to kill or absorb him. Even if he had been clever enough with words to find a way to justify just reading the man's mind and leaving him alive, when he supposedly hadn't been reluctant to absorb Dr. Itoh, SEELE would have killed him as soon as Tabris was done. Failing to save a planetary human wasn't quite as bad as outright killing them, but for a being who was supposed to preserve their lives?
He had to set a good example, not just for Shinji's sake but for Rei's. If all the angels she knew were remorseless destroyers, then what was she supposed to think of herself? That it was alright for her to let Gendo use her to end the lives of this world, since that was what angels did? No.
Shinji had begun to give Asuka some lessons, Tabris was sure he'd mention that, but he was also sure that Asuka would prefer mental combat to patching someone up. If he did let her in, she would most likely yell at him about how stupid he was, risking his life for an ungrateful bastard like that. Also, if he died Shinji and Rei would be sad, and that would be annoying to her.
It would be very inconsiderate of him indeed, to die now and leave all the work of protecting them and this world to Asuka, he thought, smiling as he stretched out on the head of his Eva. Ensuring that he was unobserved was a simple matter, even with what had once been Naoko to avoid while fiddling with the security camera feeds.
Sohryu was the sanest of the souls in the other Evas because the bodies of Evas were far closer to angel than planetary human. A planetary human mind that attempted to transfer itself in would not be suited to such an existence, even discounting the years of isolation Unit 01 had experienced. Naoko had not had any warning or preparation. Yui had attempted to transfer herself intact, and been the most damaged because of it. Asuka's mother had attempted to impress her spirit, her will upon the Eva. Instead of desperately clinging to life or trying to become a god, she'd filled that vessel with the will to protect her daughter and the world.
That which was her as a planetary human had been left behind, most of her personality traits discarded as unsuitable to her new existence. Sohryu could not be considered the same person as Dr. Sohryu (not that Tabris would try to argue with Asuka about that), but she was as sane as an experimental warrior angel could be expected to be.
The only experimental part about Tsukiyomi, on the other hand, was what Tabris had altered to disguise the fact that Tsukiyomi's mind and soul had been designed and seeded by someone who knew exactly what they were doing.
Tabris was quite comfortable resting here. Tsukiyomi had a physical AT field, since he was after all an Eva. There was no need for Tabris to make an effort to sync with him: while the other pilots had to make an effort to open up their AT fields in Asuka's case and get Naoko to open up in Rei's case, the amount of contact between Tabris and Tsukiyomi was entirely at their discretion.
Right now there wasn't any need for Tsukiyomi's hand to be moved by the mind of Kaworu Nagisa as though it was his own hand, so now that Tabris thought about it, he wondered what Ritsuko's equipment would measure their sync ratio as. This was the general 'I'm fine' level of passive contact common among family members: even some Lilim reported being aware when relatives or loved ones died or were injured.
It must cause them so much extra worry, to not know if family members were dead or alive the instant they were out of one's sight… Imagine if every time Shinji went out to fight Tabris had no idea what was happening until it was over! What was that book series with the clock that said where all the family members were: asleep, at work, in mortal peril? Strange that even in a series where humans had 'magical' perceptions, the Lilim writer still thought they would need a device for something so basic.
Tsukiyomi really didn't have any mental defense training whatsoever: the young Eva mind still wasn't quite up to controlling his own AT field without Tabris directing him. He would only be able to fight the way Yui had if he went berserk the way Yui had and sheer rage let him focus his soul, if in a clumsy fashion. Not unless Tabris copied his full combat data to him, which he was very reluctant to do. No, forget the combat data: it was the terraforming systems that really made angels dangerous to populated worlds.
It wasn't that Tabris didn't trust Tsukiyomi, it was that Tsukiyomi was young and still developing a personality. Tabris had been divided between naming the Eva spirit Hoshigami or Tsukiyomi: he'd settled on Tsukiyomi when the influence of all those battle simulations made the new spirit less interested in terraforming than combat, more willing to fight than to wait patiently and nurture. It would have been terrible if the angel's Eva was enough of a true angel to hate hurting others: dragging an innocent child who flinched from every blow no matter the target onto a battlefield? Yet the fact remained that Tsukiyomi was willing to use his power to harm others, so until Tabris saw proof that Tsukiyomi was beginning to learn the responsibility that came with power and would restrain himself from crossing any lines, Tabris simply wasn't going to give him too much power. To do so would be to tempt him to experiment with things he didn't know how to control or how to use responsibly yet, since Tsukiyomi really did want to protect the world he'd seen above him when he was turned on.
The desire to protect made people more dangerous than anything else.
Resting here with his Eva meant that Tsukiyomi would be aware if Tabris was in any real distress, and would warn him in time to get Shinji. It would have been nice to lie here without having to think or call up damaged files for awhile, but Tsukiyomi wanted to know how his pilot had gotten hurt. Tabris was trying to think of a tactful way to say, "I just ate your other father's soul: It really didn't agree with me. And oh, by the way, I found that he'd programmed you to tear mine into little bits, then eat about half of them, the ones with more memory data, less will and the S2 engine, so he could use you to escape the Moonbase and warn the UN about SEELE, not to mention give them data on what angels really were and how to counter us that wasn't distorted by the beliefs of SEELE's cult."
Actually, why was he trying to find words anyway? They were such an inefficient method of communication, even if he did mostly use them even with Shinji because both of them needed to stay in practice communicating the Lilim way. If the Eva didn't contain hardware programmed with words, the biological portion of it wouldn't have been up to learning them for at least another year, so best to keep it simple and use telepathy like normal people. Tsukiyomi hadn't sent words at him yet either, just mental nudges, anxiety for Kaworu's sake and the desire to know what the threat was, whether it had been dealt with or Tsukiyomi needed to worry about it coming after Kaworu Nagisa again.
Tsukiyomi always thought of him by his human name, the name in all his files. Kaworu was well aware that the Eva knew he was an angel, but the Eva's other father had firmly believed that the Eva series was supposed to defend humans against angels, not be turned against humanity to help angels destroy the world by SEELE. Since Kaworu was in fact human, even if he was not a Lilim, he'd respected Tsukiyomi's desire not to betray anyone and never forced him to acknowledge that Kaworu and Tabris were one and the same. The whole situation was too complicated for someone as young as Tsukiyomi to have to deal with it, so it was best to let him see things in simple terms for now, terms he could handle. Tabris had always intended to let the Eva broach the subject of Tabris' nature and what it meant that he wanted to defend this world when he was ready.
Bringing it up now, well, explaining it would also involve explaining that Tsukiyomi was an angel, and he didn't want to give the Eva an identity crisis or worry about hurting his builder-father.
Tsukiyomi was supposed to destroy Kaworu Nagisa if syncing with him revealed that Kaworu Nagisa was truly an angel instead of an altered human with some abilities copied from angels. Since angels were enemies to humanity and Kaworu Nagisa was not an enemy to humanity, then he was not an angel and the Eva did not need to eat the father who had given him his soul and taught him how to think beyond basic computer logic. Since the if/then statement did not apply to Kaworu Nagisa, then there was no need to mention what Dr. Bannon had done since there was no threat to his pilot.
If the Eva wasn't restrained in the cage, Tsukiyomi would have been fidgeting and shifting around uncomfortably, bothered by the nagging feeling that now both of his fathers must think he'd betrayed them.
Kaworu Nagisa because Tsukiyomi hadn't revealed the trap, and Dr. Bannon because if he had merged with Kaworu Nagisa, even if he'd only been in the edge of the older mind, then he would know that Kaworu Nagisa was an angel and yet Tsukiyomi had not eaten him.
It was a true pity, Kaworu reflected, that he couldn't bring Tsukiyomi to talk to his father. The Eva's soul was nowhere near being able to maintain two bodies at once. Like the clones, if Kaworu made him another body and moved him into it all the biological parts of the Eva would collapse into LCL, and then Kaworu would find himself in need of either another Eva or a very, very good explanation. Nor could Kaworu participate in a conversation like that even if he could bring the two of them together, since it was now theoretically possible that Dr. Bannon, after going over the files he'd copied, would be able to figure out how to actually kill Kaworu. He couldn't take that risk right now.
It would be possible for Shinji to act as a relay, letting Tsukiyomi move him the way a pilot moved an Eva, but Tabris didn't see Shinji letting the Eva do that anytime soon, not when he hadn't told Kaworu that someone was trying to kill him. The Eva hadn't known for sure that there was nothing Dr. Bannon could do to actually harm Kaworu without using the Eva, so he'd still left Kaworu in danger even if he hadn't let himself be used to harm Kaworu.
There really wasn't much Kaworu could do but keep lying here, proving by his presence that he still trusted Tsukiyomi, although he decided to reinforce that knowledge with soothing thoughts and by stroking the Eva's helmet a bit.
Dr. Bannon thought the Eva didn't have a soul, since unless SEELE snuck someone up to the base it hadn't had a chance to absorb one. Unless they'd fed it Dr. Itoh, although Kaworu had awoken the soul now called Tsukiyomi, moonshadow, well before then so the new mind could benefit from the simulation training. If the doctor had his way, (part of) Tabris would have become the Eva's soul, the angel becoming in truth what SEELE had told Dr. Bannon he was, a defender of humanity instead of a destroyer. It was elegant.
"Your other father wanted you to protect this world. You already have." By helping Kaworu stop Shinji and Rei from setting off Third Impact. "I'm not angry at you at all, and neither is he. You shouldn't have been in a situation like that in the first place. You shouldn't have had to make a choice like that. He was in far more danger than I was, so he needed more protection than I did. You weren't wrong."
The young behemoth was still far from comfortable. Tsukiyomi already wanted to go home, where the gravity wasn't so strong and the people working on it were his other father and his familiar tech staff instead of ones that had been working on other Evas and made the LCL he was submerged in here, instead of being out in vacuum like normal, smell of them. The Eva was homesick because this place stunk, and now his father was somewhere else, so home wasn't the same anymore? Evas were kept inside here so he couldn't even look up at home, and he didn't like it.
The uncomfortable, antsy feeling from worrying if his fathers were upset and he'd done something bad had just contributed to the desire to get out of this place.
Pleasepleaseplease? If soul-father really wasn't mad, wouldn't he prove it by getting Tsukiyomi out of this horrible place? Soul-father wasn't punishing him, was he?
Feeling Kaworu waver, the Eva pressed his advantage. Please? Just for a bit, so he could move around? Ooh, maybe a live fire exercise?
"I'll talk to Ritsuko," Kaworu promised, conveying that it wasn't his decision but that of the human with shiny things on her face and yellow headfur.
Tsukiyomi was grumbly. Other-father was definitely better than Ritsuko. Other-father would have let him run around for testing.
Kaworu decided not to explain to the Eva that Dr. Bannon thought he was just a tool, unless he'd happened to see what Kaworu did to his creation while he was in the angel's mind, in which case he might think the Eva was evil now. Kaworu would have to ask Shinji about that too, when it was time for Shinji to come back.
When the next movie comes out and I figure out how to incorporate Mari into this, I'm thinking of giving her Tsukiyomi as her Eva, by the way. They will get along smashingly, by which I mean they will smash a lot of things.