Told you, Marcos have an amazing agility even for a fox, and is quite strong, but that isn´t free. Use that skills consumes his energy quite fast depite his training, because (A) foxes aren´t made for fight , and (B) he have his breathing troubles remember? So sometimes he ends really fainted when he trains hand to hand against Dora or other sparring rivals if he forces himself too much. In a normal fight, he would KILL the rival in a few secodns to prevent that, but obviouslly can´t do that against his friends or partners. In this specific case, Dora´s stamina is largely superior to Marcos one, amd they can be a little too energic during the simulated fight, until...

should be sleeping since long but did a few sketching practices, that failed, and this was a derivate

Don´t worry, will take around half hour, but Marcos will be fine and his friends will take care of him (but Breihzlander will have a serious talk about the care of his health, because scared him as hell)