oh i have not thought about this at all hold on. ill answer for who i can come up with decent answers for
celeste - shes actually quite used to loss. her go to emotion is frustration and anger i think. not in a destructive way but in a angry cry sort of way. if shes upset enough i think she'd start snapping at people
willow - cry, cry, and cry some more. hes a sopping wet little guy hes a crier for sure
aether - shut everyone else out and isolate himself. he hasnt lost lives before but he has lost friends and his answer to that was cut off everyone and make sure he could never form a meaningful relationship ever again so there would be no repeats. i guess this means aethers method of coping just in general is self destructive behaviors
teles - smoke. teles's answer to negative emotions is usually go smoke