Robin Hood

A Solo Servant forced into Tamamo’s army after she recruited him using her Regalia.
Robin makes sure to diligently follow Tamamo’s orders, as any disobedience causes her to bestow upon him an electric shock. Poor. Poor Robin.
He thinks rather highly of the Main Character, so the friendliness that he demonstrates towards him or her is genuine.
If the opportunity arises, he intends to defeat Tamamo and obtain his freedom by taking the Regalia. He fully intends on selling off the Regalia for a quick buck.
Due to their numerous similarities, he is distrustful of Archimedes.
In the side story, he aims to beat Tamamo and also capture Medusa’s (Rider’s) heart.
…Note that the above is what we could discern from the scribblings we found on a certain someone’s PC.

Fate/EXTELLA material: Encyclopedia of Fate EXTELLA