cui faveam potius: i. e. in whose success shall I feel the most lively interest? With the question and answer cf. Catul. 1.1ff. “cui” is for utri, as occasionally in writers of this and the following periods.
 per facta exhibita: the friendship may have been proved by withdrawing from rivalry with Catullus in his affair with Lesbia; but if Caelius be Caelius Rufus, we must suppose the withdrawal was but feigned, as Catullus afterward discovered; see Intr. l.c.