Kalliades is a Macedonian and close in age to Alexander himself so it is quite natural that they became friends, even before entering the mountain. In fact, Kalliades was a regular drinking companion of both Alexander and Hephaeston and also took the latter's death quite hard. Not as hard as Alexander, of course but that was different.
Like all those people who suffer from deep passions and emotions, Kalliades is a natural entertainer and is always smiling, it would seem. Few would imagine how close he came to - just like Alexander - drinking himself to death when Hephaeston was taken. He was - privately - a nervous wreck when Alexander was on Thanatos' doorstep.
Odder yet is it too see how jolly old Kalliades and straight-laced Neshaa became such firm and inseparable friends but they have been known to debate late into the night while sharing guard duty or even when not.
There is an awful lot more to Kalliades than people think because they rarely see beyond the dancing eyes and smile.