Dark Souls was one of the few games where I feel like the partners were legitimately useful and not just there for plot depth.

Black Iron Tarkus is pretty Nito.

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The Beast in Kingdom Hearts. Right when you drop to your lowest point - you lose your only form of attack, your two companions throughout the whole game abandon you - you get a kickass party member who pretty much carries the level for you. It's such a variation in gameplay, and the character himself actually has some depth compared to his portrayal in the movie.