ooooohhhhh good, im so pleased you feel better about sunny. just remember that everything is new to you both and things will turn out great between you both, as long as you keep him in line with correct training!

for sunny to be more comfortable with your brother, he can also help you train him. if your brother does some small things like asking sunny to sit, give paw or lay down to start with and also give him treats when he does the exercises with him. sunny will begin to trust him more because treats will be involved. your brother could also make up sunny's food and give it to him, because again food is involved again.

if sunny is comfortable with your brother then i dont see any problem with your brother walking him, feeding him and also helping with training. 5 minute training sessions to begin with, then he can make them longer and 20-25 minute walks and then make them longer.

hope this helps!