Back in the day, Methos was Egeria's host and the catalyst for her change of heart. Post-Horsemen, even though that means changing the date that they rode, so he knows the temptation and appeal of power and has gotten over it. So they Tok'Ra around for a while, then get caught, Methos "killed", Egeria imprisoned. Fast forward to the present; for some reason, Methos is with SG-1 when they find Egeria.