Disclaimer: I don't own BTTF.

Author's Note: This chapter features Doc's side of the equation, as he sets out to ensure Biff doesn't kill off his past self. Now that would be... messy.

Chapter Twenty-Six

Saturday, November 12, 1955
09:25 PM PST
Hill Valley, California

Doc felt like his veins were filled with pure adrenaline right now, as he was flying the train over to the town square. The day had been long and miserable. He still remembered that morning, and how he had been talking with the older version of Marty for the last time… only it hadn't been that morning, it had been on a day that wouldn't come to pass for another sixty years. As for the reality he'd been in, it was long gone by now – and Doc hoped that today he would be able to make sure it wouldn't come back.

"Are we there yet?" Clara asked him, putting a hand on his shoulders. "I thought I knew Hill Valley by now, but I've got to admit that I don't have a clue about the paths by which you're taking us to our destination."

"Well, a lot has changed in sixty years" Doc replied. "But yes, we're almost there. Just two more blocks, and we should be at the Square." He sighed. "I just hope Biff won't have any trap set for us. I keep thinking of him as some dumb old fool – but I've been doing that too often on this journey, so I prefer overestimating him now."

"I guess I understand what you mean" Clara said. "Buford Tannen was dumb, too, and he didn't learn from his mistakes. Biff appears to do so – or at least, his 2015 self does. Although I still doubt he could outsmart you."

"Well, thank you for the compliment dear, but we've got to keep all options open" Doc said, sighing. "And even if he can't outsmart me, he might be able to do so with my younger self… ah, there we are."

The seventy-five-year-old looked around as they entered the town square. The familiar wires had been set up and Doc could see the clock turning to 9:26. Only thirty-eight more minutes until the lightning strike. He wasn't sure whether they had the time to fix everything, but they could certainly try.

"Where are you, Dad?" Jules asked, thrilled with the possibility of actually seeing a younger version of his father. "Aren't you supposed to be working on those wires like, right now?"

"I believe I was inside at the moment" Doc muttered. "Which is for the best – that way, at least he won't be there when we confront Biff." He scanned the sky. "I hope he'll show up soon – my younger self isn't going to stay in there forever."

"You think he might have stayed at the dance instead?" Clara asked. "He's certainly shown that he can fool us. Maybe he just flew off to the square and then turned around, or something like that."

Doc nodded. "Perhaps" he muttered. "Too bad the time tracker can't show me the exact location of the DeLorean right now. If it did that, chasing Biff would be much easier. Could be an idea for future modifications."

"No time for ideas right now, Emmett" Clara reminded him. "We need to look for Biff."

"Indeed we do – ah, there you are" Doc replied, looking outside the window as the DeLorean came flying in. "Now, what do we do about him."

"You haven't got any clue?" Clara asked. "Shame on you, Emmett. I would have thought you'd have this prepared into the tiniest detail."

"I would have – but I haven't really had time to think this through" Doc replied, looking out of the window. "Hmm… doesn't look like he's landing."

"Does that matter?" Clara asked.

"Well, yes, because I thought he had something in mind regarding my younger self" Doc replied. "It would be much easier to stop him out of the car. Ah, well." He grinned in a slightly scary smirk. "If he's not landing on his own, we'll just have to help him."

"Emmett?" Clara asked, raising an eyebrow.

"Watch" her husband replied, accelerating the time machine's speed. The train chugged into the Square, headed straight towards the DeLorean.

"Are you planning to ram him?" Verne asked, excited.

"Of course not, Vernie" Doc replied. "That would be too dangerous, both to us and to the alternate time machine… I'm not sure whether I could care less about Biff at the moment." He sighed. "But we might be able to force him to land this way… ah!"

Doc steered the time machine over the DeLorean with a swift maneuver, and immediately started lowering. Naturally, Biff attempted to fly forwards, but Doc simply went along with him, while continuing to lower.

"What are you up to, Dad?" Jules asked.

"The DeLorean's hover circuitry has the peculiarity that it automatically disengages itself once you're on the ground, and you have to stand still for it to re-engage again" his father explained. "Furthermore, the time machine will propel itself into the sky a reasonable distance once the hover circuitry is activated – too much for Biff to get out safely. He would simply end up with a collision."

"Ah" Clara replied. "But does he know that, too?"

"He should, considering what we've seen of his knowledge of the DeLorean so far" Doc said. "But we'll deal with that sooner or… ah. He's stopping."

"And now what?" Clara asked. "Simply hover over him until he caves in?" She frowned. "Perhaps he'll simply get out and he'll try to destroy the train from underneath."

"I doubt Biff's limited knowledge of technology will enable him to do that, darling" Doc responded. "Besides, there are few circuits available under… ah, he's getting out."

"He should, 'cause that sounded like the car door hitting the train" Jules said. "You don't think that'll damage anything, do you?"

"Nah" Doc replied. "Both the train and the DeLorean are sturdily built." He looked outside as Biff was running up to the Courthouse. "Great Scott!"

"Do you think he's going to kill you?" Clara asked, shivering.

"It might not have been his original plan, but it probably is now" her husband replied. He rapidly landed the train in front of the DeLorean. "You stay here and guard the kids. I'll go after Biff."

Clara nodded, as Doc got out and ran after Biff, towards the Courthouse doors. It had been quite some time since he'd had this amount of exercise, but he figured it wouldn't be easy for their opponent either. After all, Biff was 79 by 2016, and he'd been walking with a cane in 2015.

"Stop!" Doc called out. "Right now! You're causing potentially irreparable damage to history!"

Biff turned to him and smirked. "What makes you think I care, Brown?" he retorted. "You've caused damage to my life!"

Doc frowned. "What exactly do you mean by that?"

Biff growled. "Everything" he replied. "It was your time machine that allowed Marty McFly to go back to 1955 and ruin my life. He convinced that no-good Irish bug George McFly to stand up to me and start dating my girl. He thwarted my almanac scheme. He ruined my car! Everything that made my life hell was the fault of you and that teenaged brat!"

"It was necessary for the preservation of the space-time continuum" Doc replied. "And you've not exactly been kind to us, either."

"But you won in the end, and that's what matters" Biff replied. "And it's about time I reverse that trend." He continued his run towards the Courthouse doors, and Doc followed him, noticing that he wasn't walking with a cane anymore. His health had clearly improved since 2015, which made him a more dangerous adversary.

Biff was about to swing the door open to get in, when the door swung open against his head. Doc gasped as he saw his younger self get out. 1955 Doc frowned, and looked at Biff. "What the…" he muttered. "Driff Tannen? But you're dea… who are you!"

Biff growled, and then he got out a knife. "Prepare to realize that" he hissed, as 1955 Doc paled. 1985 Doc paled as well, realizing his younger self – and thus he, and Clara and the kids – was only seconds away from death. Seeing his counterpart was too paralyzed to do anything, he decided to take action himself. With Biff distracted by his younger self, he ran up to him, fully intending to smack him out of the way.

In the end, Biff ended up seeing him one second before he hit. The bully was barely able to take a step before Doc slammed into him. The attack had the intended effect – Biff's knife shot out of his hand, merely grazing 1955 Doc's leg – but Biff remained standing. Having lost the initiative, he decided to run off.

1985 Doc looked up, relieved – and stared right into his younger self's eyes. The thirty-five-year-old paled, gawked and subsequently fainted. His older self could narrowly reach out to stop him from falling on the pavement. One look down told him Emmett had earned himself a nasty bleeding in his lower leg. However, it didn't look like the attack had damaged anything vital. His younger self would live – and nearly as important, he would be able to help 1955 Marty get back to the future tonight.

He then heard the start of an engine and looked up to see Biff activating the hover circuits of the DeLorean. "Damn!" he cursed, running up to the time machine in a futile attempt to stop him. As he did so, though, he suddenly felt a sensation of pain in his left leg which stopped him for a few moments. He winced, trying to stay upright and willing the pain to go away. After a few seconds, it did just that, but one look up told him the DeLorean was already flying out of the square.

Doc shrugged and walked over to the train, where Clara was looking at him anxiously. "Are you all right?" she asked him. "Uh, both yous?"

"We're alive, if that's what you mean" Doc muttered, getting into the train. "Why didn't you take his DeLorean?"

"I tried, but I couldn't get it open" Clara said. "Biff managed to get inside by destroying the system, as you'll remember, and I wasn't sure how those locks operated. I was afraid the electricity might electrocute me, and, well, I didn't really think it was urgent. Only after Biff got back here I realized I should have risked it, but then it was too late."

"I see" Doc muttered, understanding. "I suppose I can't blame you for that."

"Are we going to go after him now, Dad?" Verne asked, thrilled.

"Not right away, I'm afraid" Doc said. "I'm afraid seeing me got my other self in a state of shock that allowed him to lose consciousness. We need someone to revive him, and distract him from that bleeding in his leg enough to go through with tonight's scheme – and I can't be it, as seeing me would either create another shock, in which case it would be useless, or leave him with information he shouldn't remember. Better for him to think that he knocked himself out against the door or something like that."

"Then who do you want to send out there?" Clara asked. "Me? Your younger self wouldn't know me…"

"No, but I know me" Doc said. "Remember when we first met? If my counterpart saw you, he'll be instantly smitten with you and he will certainly try to find out who you are. We need someone to get him back on track with getting this time's Marty home."

"I see" Clara replied. "So that means that, unless you want to retrieve Marty…"

"…who won't be suitable either, since my younger self will undoubtedly think he's the other Marty, and he will not allow him to leave again…"

"…it'll have to be one of our sons." Clara looked at her boys, then back to her husband. "And in that case, Jules would be the better pick. He looks the least like you."

"Hey!" Jules exclaimed.

"From the outside, sweetie" Clara assured him. "Though that raises a problem – Jules, you will have to pretend you're a regular child of this time period just passing by. Under no circumstances can your father's counterpart be allowed to know you're a time traveler."

"Indeed" Doc chimed in. "You'll have to adjust your vocabulary a bit, Jules."

"Will do, Dad" Jules replied. He eagerly ran out of the train, and towards the Courthouse. Doc stared after him, then called out: "Jules!"

Jules stopped. "What?"

"We're going to move the train out of sight" his father replied. "Get around the corner once you're done. And don't let my younger self see where you're going."

Jules nodded. "All right" he replied, resuming his run towards the Courthouse. Doc stared after him for a moment, and activated the train's engine.

He was barely on the move when his walkie-talkie jumped to life. "Doc?" Marty's voice sounded. "Are you there? Over!"

Clara picked it up. "Marty, this is Clara" she replied, trying to fiddle with the controls of the futuristic device.

"Clara?" Marty asked. "Where's Doc! Is he…" Marty's voice wavered. "…all right?"

"Don't worry, Marty" Clara ensured him. "Emmett is just piloting the train into a more inconspicuous place… it's a long story."

"Tell him to wait outside the dance, we'll be there in a few minutes to pick him up" Doc replied. "He can keep an eye on his parents, too."

As Clara relayed the information to Marty, Doc flew the train over the road and towards the place he had designated for it, behind the Courthouse. Clara finished the conversation with Marty at the same time, and she handed her husband the walkie-talkie as they both waited for their oldest son to reappear.

It didn't take long. Within a minute or two, Jules climbed back into the train, grinning broadly.

"How did it go?" Doc asked.

"Perfect" Jules replied. "I don't think he realized who I was… he did give me one strange look, but when I saw him, uh, you last, he was heading back to the wires over the street." He looked at his father. "What time is it?"

"Nine-forty-four" Doc replied. "Time to get out of here and make our way toward the Lyon Estates housing development – Biff's final target, most likely. The Marty that is about to be sent home will be here in ten minutes, and we need to pick up our Marty as well."

"Good point" Clara said. "Although it's too bad we can't see you help Marty home through the lightning strike, though."

"And what are we going to do after picking Marty up?" Verne then asked.

Doc sighed. "After that we follow Biff again" he muttered. "And let's hope that this time, we'll manage to defeat him. We will have to – there is no other option left for us."