Answer: One would certainly think so, since ti and mí are the prepositional pronouns for "you" and "me" respectively. But the preposition entre is an exception among prepositions: its objects use the subject pronouns, not the object ones. Thus it is perfectly proper to use phrases such as entre nosotros for "among us," entre ellos for "among them," or entre ustedes y yo for "between you (plural) and me." (Sometimes the unusual phrase entre sí is used to say "among each other.")
The same pattern is followed for the less common preposition según, which usually means "according to." Thus the phrases según tú and según él are used for "according to you" and "according to him," respectively.
