Felix standing up to Saturos and Menardi at the top of the Venus Lighthouse to convince them to let him take Sheba back to the ship, despite being very out matched and standing no chance against them.
At the end of Golden Sun, due to an earthquake, Sheba falls off of the Venus Lighthouse, most people would let out a Big "NO!" and sob as they failed to save someone. Felix jumps off right after her to save her and succeeds without any injuries.
Golden Sun: The Lost Age
Beating Poseidon, something no one had ever done before.
The sheer determination of the party to light Mars Lighthouse, despite the Wise One's interference.