i've honestly been rotating this one in my head for AGES but kind of a different form of it? just some idea of ivan time traveling to the future where he discovers he's dead and he knows that in order to arrive to this future where at least till is safe and alive, he needs to go back to his own timeline and do whatever he needs to. except till won't let him go because how can he when this is the last time he'll ever see ivan? another thought i had about this was an au where till is the one who time travels instead and finds himself face to face with... well, himself, but more importantly a version of him who's been changed irrevocably by ivan's death. regarding these two ideas, i'm still working on it because i desperately (like you have no idea how desperately i've talked to maybe a dozen people about it trying to ram my head against this plot) want to write it, but i haven't figured out how it would end. in the meantime, since this answer came so so late, a brief dialogue scene i imagined (without context, per usual).

//

Ivan takes one look at the Till's pale, frozen face and knows the truth. "How long have I been dead?" he asks, feeling calmer than he sounds. He sounds quiet and uncertain; emotionally, he feels very distant from this situation as a whole.

Till's throat bobs when he replies. "Three years. Eight months. Nineteen days."

"You remember it down to the day?" Ivan asks, surprised.

"How could I not," Till manages.