The twins are close and seem to be very alike during the appeaances they make throughout the series. On many occasions, they seem to have the same thoughts and a similar trail of thoughts, leading them to understand each other quite well. The two will commonly address each other when speaking about something which seemingly excites them and they seem to care much about each other. Though they are very similar, they have clear differences as well, such as Esquerdo being more accepting of the consequences of the world and doesn't necessarily feel the need to affect it. He's a free-spirited man and believes in the honour of fighting fair and square as a mercenary. Derecho, on the other hand, is a bit more serious and considers things on a more internationam level. He is also the older brother and seems to be the more mature one of the pair.
Originally, they weren't very impressed by him and almost found it downright insulting to be faced with a young, beautiful child that they assumed had received his title from his looks. During the mock battle, they acknowledged that they had underestimated him and they were very impressed with Mahmut. It appears as if they harbour a lot of respect for him as a warrior and they believe in his skills on the battlefield.