i think it's actually pretty fascinating that Henry didnt know for certain that Eleven would help him too. He probably hoped she would, maybe even expected that she would. Gave enough hints here and there in hopes that she'd take the bait and free him of his little mental block, he didn't know for certain that she would, yet he still gave her that out.
He gave her the instruction of how, and created an opportunity for her to get out, not knowing if it'd be his own freedom, or his end.
Because surely they'd have killed him had she not helped him too, right?
Brenner would have known he'd helped her get out, he'd have known that Henry was the one who freed her given how friendly Henry had been being toward her, so he'd have probably been killed for his involvement in freeing her. Brenner would have either killed him, or pumped him so full of electricity that he'd be comatose for months, maybe even reduced to how Terry is now.
Yeah, Henry is awful, yeah he killed all the other kids, but why help Eleven?
Why was he so fond of her? Given how distant he was toward everyone else.
