In the Alvin and the Chipmunks: The Junior Novel, Alvin is confirmed to be the middle child, de facto of a statement that Simon is the oldest.
Alvin retains some of the traits he possessed from the 80s such as his impulsiveness, desire for fun, and charm as seen in Alvin and the Chipmunks: The Squeakquel where he manages to capture the attention of a group of girls using his cute looks and as well as the French language (e.g. he called Becca Kingston Mademoiselle after kissing her finger). Nevertheless, he has difficulty at showing affection toward Dave such as in the first film, Alvin and the Chipmunks, where he struggles at telling Dave that he loves him as a father, but less so with his brothers such as the time Alvin tried to kiss Simon to cheer him up in the second film