how does iago make himself seem to be an honest friend to cassio in the aftermath of the fight

Cassio laments that he has lost his reputation, which is very dear to him. Iago tries to convince him that a reputation means little; and, if he talks to Desdemona, maybe he can get her to vouch for him with Othello. This will help Iago hint that Desdemona and Cassio are together, which will enrage Othello. Iago then gives a soliloquy about knowing that Desdemona will speak for Cassio, and that he will be able to turn that against them both.