I've seen a few people say that in round 7, Ivan only brought Till pain. Here's a ramble on why I don't think that's the case:
Till steps onto the stage in round 7 with a renewed vigour. He had given up in round 6, which appears to have been at most a few hours ago. With Ivan's death in the previous round, Till chooses to fight – he chooses to honour Ivan's sacrifice. At the start of round 7, Ivan is his strength.
But then Luka begins to manipulate Till with VERY fresh wounds (again, round 6 only just concluded). Till begins to crumble by being reminded so vividly of the grief he is trying to suppress. He is flooded with regret, he is guilty, he blames himself. He cares about Ivan so much that his grief manifests physically with his nose bleed. He desperately tries to cling on but the loss is almost too much to bear–
And then he sees Mizi.
Mizi – the girl he loves, the girl he thought he lost, his beacon of hope – appears in the crowd before him, and he is reinvigorated once more. Ivan is dead but Mizi is alive. He's not just fighting for a ghost but also a tangible, living person. She gives him the strength to press on and try to complete his goal – to live for Ivan.
While Ivan causes Till pain in this round, Till struggles to fight through that pain FOR Ivan. Ivan acts as both his weakness and his strength, and I don't think it could have been done any other way with how close together the two rounds are. The grief is too fresh not to haunt him, no matter how determined he is to make Ivan's sacrifice mean something.
So yeah, in short Ivan causes him pain AND motivates him to fight. If Luka wasn't such a manipulative bastard, I think Ivan would have acted mostly as Till's strength in round 7.
