Vito, Thorn of the Dusk Rose

In a Two-Headed Giant game, life gained by your teammate won't cause the ability to trigger, even though it caused your team's life total to increase.

If an ability triggers whenever an opponent loses life and causes you to gain life, such as the ability of Exquisite Blood, this will loop until either you win the game or a player takes an action to break the loop.

Because Vito's first ability doesn't deal damage, you won't gain life when it resolves if Vito has lifelink.