You could intercept their communications and replace the public key one sends with your own, and when the other tries to send a message to the first (to your public key instead of the cat’s) you get access to the message’s contents and then reencrypt it to the correct public key.
0% because cats encrypt their communications with AES256
You could do a MITM attack while they exchange public keys
You can’t decrypt anything with the public keys though, wouldn’t work
You could intercept their communications and replace the public key one sends with your own, and when the other tries to send a message to the first (to your public key instead of the cat’s) you get access to the message’s contents and then reencrypt it to the correct public key.