Ivan Ilych's experience of illness and dying in The Death of Ivan Ilych is defined by a growing sense of isolation. His suffering and his fear of death have the effect of completely cutting him off from the normal world around him. For his friends, colleagues, and family members, life goes on just as before. Ivan is dismayed to discover that none of them seems to understand or care about what he's experiencing. He is left to face his fears and agonies alone, without comfort from anyone except a servant, the one person who pities him.
Gerasim is the only character who can comfort Ivan because he can understand what Ivan is going through, and this is because Gerasim fully understands his own mortality.