James Potter generally considers himself to be an intelligent and observant person. Of course, he also considers himself charming, handsome, athletic, and a host of other things, particularly since Lily agreed to go out with him. But sometimes, he's just plain dense.
The first thing that struck him as odd was the lovebite on Remus' neck. Not that Remus never had girlfriends- but he always made a big production out of taking them on dates, like romantic picnics and even the occasional trip to Madame Puddifoot's before he even considered going further than holding hands. So, a lovebite when Remus didn't have a girlfriend was odd.
When questioned, Remus told James Sirius had left it. This was obviously insane, so James went to hunt down his best friend.
Sirius, unfortunately, was often insane. "Have you seen the hickey on Remus' neck?" James asked when he found his friend, in the dorm flipping through a magazine he quickly hid when James walked in.
"It's a beaut, isn't it?" Sirius said with a whistle. "One of my better efforts, if I do say so myself."
"You.. are very strange," James said, and left to go find Lily.
The second thing that struck James as not-right was the way Padfoot behaved on the full moons. He'd always been playful with Moony, but they suddenly began... well, James' stag mind processed it as flirting.
And at the end of the night, when they were back in the Shack and Moony was too worn out to cause any more trouble, the two canines would lie down, curled together. Sirius refused to leave with the rest of them, insisting that sticking with Moony through the transition helped. James gave up arguing, which was difficult anyway when you were different species, gathered up Peter, and left.
The third change James noticed was rather mundane, really. Remus stopped eating strawberries. He'd always enjoyed the fruits, almost indecently so, when they were served with breakfast or as part of a desert. And one day he just stopped eating them.
When James asked if something was wrong, Remus just told him, "Sirius is allergic." Which James already knew and didn't even begin to answer the question. Sometimes, Remus could be as odd as Sirius.
The fourth sign that something new was going on came when he found Remus asleep in Sirius' bed one afternoon. Sirius sometimes crawled into bed with Remus at night, usually either when Remus was still suffering the after effects of the moon or Sirius had a bad dream, but Remus napping on Sirius' bed was unusual.
Just as he was contemplating waking the werewolf up and asking if he was feeling okay, Sirius came out of the bathroom. He caught James looking at their friend and smiled. "He's exhausted. Been studying too hard. Hardly has any time for fun these days," he told James.
"It's best to make the most of the time you've got," James said, not really answering anything.
"Yes, yes it is," Sirius said happily, and grabbed his trousers where they were pooled at the side of his bed. James noticed only then that Sirius had been wearing just boxers and a t-shirt. He'd probably gotten into some sort of mess and had to get a clean shirt. Sirius got into messes and had to change clothes mid day often enough, although James usually at least knew what had happened.
The fifth sign that something had changed was the fact that Sirius stopped dating. Didn't slow down, didn't fall madly in love with a single girl and swear off all others, just stopped. For the previous Sex God of Hogwarts (a name Sirius had thought up for himself, but quite a few people, particularly girls, used) swearing off the dating scene was highly irregular, to say the least.
James' first thought was that Sirius had caught something from one of the girls, some of whom weren't much pickier than he was. But that wasn't the kind of thing he could just come out and ask, even if it was Sirius. So one day when the rest of his dorm mates were gone, James put a quick spell on the landing to alert him of approach and went through his brother's drawers.
He found the expected stash of condoms, but also a bottle discretely labeled Anal Lube. "Way to go Sirius!" he whistled, impressed. He'd heard that doing it that way was great, felt even better than the regular way some times, but he'd never tried it. Judging by the almost empty tube, Sirius definitely had. But no potions or pills to indicate Sirius was sick.
James was about to search under the other boy's mattress when the room flashed red, a sign that someone was coming. He quickly muttered, "Finite Incantum," and stepped away from Sirius' bed just as Remus walked in.
Not wanting to shock his innocent friend with discussion of things like anal, which he doubted Remus had even heard of, James retreated to his own bed to think. Maybe, Sirius wasn't sick. Maybe he'd just found someone to experiment with, and the sex was so great he wasn't playing the field any more. There could be tons of reasons for keeping it secret- maybe she was worried about her reputation, or it could be someone from Hogsmeade and Sirius didn't want any one to know he was sneaking out. It could even be a Slytherin. James resolved to watch his brother more closely and put the problem out of his mind for the moment.
The sixth sign that something was up with Sirius was catching him talking to Lily. They had developed an uneasy truce since James began dating her, but they never went out of their way to spend time together.
Except now, apparently. James had noticed that Sirius and Remus had been ignoring each other for the past couple of days, and he wondered if it might have something to do with that. But Lily would never help Sirius make up with Remus. She thought he was a terrible influence on her friend, and that Remus deserved friends who wouldn't get him in trouble all the time. She had no idea how often Remus masterminded their pranks, or found ways to do thinks Sirius and James thought were impossible. Sometimes, it irked James not being his girlfriend's favorite Marauder.
James asked Lily about the conversation later, but she only said, "He needed advice about something," with a pleased smile on her lips. James wondered if Lily had given Sirius advice likely to end up with him trapped in the lake with the giant squid or something, but wisely kept silent.
James finally put all of the pieces together the next day. He heard raised voices coming from their dorm as he made his way upstairs, but figured Sirius and Remus were finally hashing out whatever they were upset about and came in anyway. One or the other of them was likely to need moral support. Not that Sirius had any morals, but he could probably referee if things got nasty.
James walked in right as Remus, red in the face and obviously furious, yelled, "Because I love you, you big oaf!"
That seemed to deflate Sirius, who offered only, "I'm sorry, Moony. I do try."
"I know you do, Padfoot. You're just not used to thinking about other people. We'll get there." Remus seemed to be calmer now too, and both of them were still oblivious to James, who had paused in the doorway when Remus professed his love, thoroughly confused.
Remus held out his arms, then, and Sirius crossed the room, gratefully stepping into the werewolf's embrace and kissing him on the lips.
Suddenly, everything made sense. James made a choked noise and, as people sometimes do when completely shocked, fainted.
The thud got his friends' attention. Remus focussed on waking James up while Sirius went for Lily, who was luckily in the Common Room. They arrived back in the dorm just as James sat up. "What the hell?" he asked, still shocked.
"You fainted, mate," Sirius said with a grin.
"Have you been outside? Could you have gotten overheated? It's unusual for a person to just pass out like that," Remus said worriedly.
James almost choked on his laugh. "Not when he walks in on his two supposedly straight best mates snogging each other's faces off," he says, realizing belatedly that he probably shouldn't have outed them in front of Lily.
Everyone stares at him dumbfounded for a minute, then bursts out laughing. Remus is close enough that James can see the tears in his eyes, and Lily and Sirius seem to be holding each other up.
That's the scene an extremely confused Peter walks in on a minute later. James lying in the floor and everyone else laughing like madmen (and women, in Lily's case, although James thinks insanity might be very pretty on Lily.) "What's going on?" Peter asks, looking around.
James isn't really all that sure himself, so he lets the others explain. "He.. he didn't know..." Lily chokes out between laughs.
"About me and Padfoot," Remus finishes, getting himself under control and wiping his eyes, and now Peter is laughing too. That sets Remus off again, and now everyone is cracking up, and James is still confused.
Several minutes later, when everyone is calm, although Sirius bursts out chuckling again periodically, James asks, "So this is common knowledge?"
It's Lily who answers. "James, they went to the Valentines Day Ball together."
"They've done that before," James argues. "And they always cuddle and sleep together, how was I to know anything had changed? Why didn't you guys tell me?"
Remus frowns. "Sirius, you told me you let James know," he says sternly, obviously annoyed.
"I was afraid!" Sirius wails. "What if he'd freaked out, or said he didn't want to be my friend any more? What if he'd told his parents, and they'd been mad? I didn't want to get disowned again! And we kept letting little things slip, and when he didn't react I thought he'd figured it out for himself, and then Mum put you in my room when you came to stay this summer instead of giving you your own, and I thought I didn't need to tell them any more."
James smiles, the way he always does when Sirius calls Mrs. Potter 'Mum' and reassures his friend, "I'm not angry, and if my parents don't know, I'm sure they won't be either. I do think you should tell them, officially, but Mum's always been practically psychic about these things, so they may already know. And if they don't, they won't care. You don't have to worry about producing an heir for the Black family any more. No one minds if you're queer."
Remus still looks annoyed. "I'm sorry, James. If I'd known he hadn't told you, I'd have said something myself." He shoots Sirius an angry look and the dog- animagus hangs his head.
Shockingly, it's Lily who comes to Sirius' rescue. "Don't be mad, Remus. Sirius was afraid of losing his family all over again."
"But instead of telling me he didn't feel like he could tell them, he lied to me," Remus says, clearly unwilling to let this go.
"I didn't want you to think I was ashamed of you!" Sirius says, still upset. Remus visibly softens, right as James comes to a shocking realization.
"That's why you have anal lube!" he tells Sirius, and Remus blushes so hard James is a little bit worried he's going to explode.
"I don't know how he saw that, I swear!" Sirius insists immediately.
"I was looking through your nightstand. I thought you were sick. I thought that was why you'd stopped hooking up. I never would have guessed..." James says, trailing off. He belatedly realizes he's still sitting in the floor and gets to his feet. "Congratulations," he tells the pair, pulling first Sirius, then Remus into a hug.
When they step apart, James grins. Everything's okay. Sirius isn't sick. In fact, he's better than he's been in a long time.