since Lex is the part he buried, it is the part he is not used to. It is like a part of you and in its purest form is presented to you. I think Rowan can be kind like Lex but without being so bizarre like him? It is like you or me or anyone else. We can show our kindness to the people we love. In especial occasions, we can show be cheesy but we don't do that all the time just like Lex.
Lex is the manifestation of your affections. What he could do if care or love someone ( family, relative, a lover, a pet, etc). Remember he got a traumatic separation of his parents. They both died. the author is leaving some hints/glues for us but later, the author will touch and talk about those topics when they the MC and the ML become more close to one another.