tuus

Tuus, tua, tuum is an ordinary first and second declension adjective, and being an adjective is the point. It agrees with the thing OWNED, not with the owner: pater tuus is masculine because pater is, tua causa is feminine because causa is. English possessives agree with the owner, so this is a genuine habit to unlearn.

It is the possessive of tu and so refers to ONE person. For a plural "your" Latin uses vester, vestra, vestrum, from vos. Getting that wrong is the commonest possessive error going.

Latin leaves the possessive out whenever ownership is obvious from the situation, which is more often than English does. Patrem amat is "he loves his father" with nothing marking the "his" at all. Putting tuus in therefore adds something: emphasis, contrast, or occasionally warmth. Suus is the reflexive third person, "his own", and it is not interchangeable with eius, "of him", which points at somebody else.

The neuter tuum can stand on its own as a noun, meaning your business or your part, as in tuum est, "it is for you to".