verb agreement - "The one who wants" vs. "the one who want"

I am getting confused with usage of 's' with verb- consider following 2 sentences-

1. I am the one who wants to stay with you.


2. I am the one who want to stay with you.

According to me, first one is the correct usage, because, "the one who" is third person, and hence, the verb will get an 's'.
Would like to know what is the rule to be followed in such cases.