Disclaimer: I own nothing at all but here's a note to you guys.
I know cats can't write or maybe even read but bear with me, I'm doing pretend letter that would be sent if they could read and write. I'm doing Ashfur to Brambleclaw because they have well known dislike. You can write to me combinations of cats and idea basing, I except all types but I might not do them because of time or interest.
-Tigerstar to Sasha: love letter after they meet. (This is one I would do.)
-Any gay letter, I will chuck these out immediately but its sick (just a warning).
-Tawnypelt to Stormfur: love letter after Stormfur leaves (I'm sorry but these are an iffy if I feel like it or if it's to yell at Stormfur maybe, but otherwise I can't I get bored)
-Graystripe to Fireheart: a friendship letter to tell how he misses him [or vise-versa. (These I can do a friendly letter of interest.)