Gave Camillo letters from both Sven and Faendal.

[Jaded]

I got the letter from sven, told faendal about it, then faendal gives you a letter, then i stole svens letter back from faendal.

using this method I believe it is possible to get both Sven and Faendal to like you, maybe everyone knows this but i thought it was odd that they didn't have an option for you to present both letters at the same time to camillo even though all the options are there.

[Eternie]

Remember that Camilla can only read one letter at a time. Altough being able to hand both over would be good. Of course you'd have to get rid of the stolen tag first by fencing it.

You can be smart as well and use the letters to put them both off side with her so you can Marry her ... without competition.
Although if either of them is still alive they do come to visit Camilla in your house!