Krates was a Theban in Alexander's army, an old campaigner from the very beginning. He was one of those hardbitten sergeants you find in every army; always talking about 'the good old days' and how things used to be different or better in his time. Always telling stories of the great victories to the young bloods. He saw it all and was heroically involved somewhere.
The newer warriors smirked and commented behind his back as they always will.
Only Krates was not exaggerating. He has saved Alexander's life twice and did so again, years later in India, coming a spear's width from being trampled by an enraged elephant.
In fact, Krates has remarkably few scars for someone who has come so close to dying as many times as he has. He's broke charges with disciplined phalanx counter charges. He's routed elite cavalry flanking maneuvers no-one else saw coming.
Krates, you see, has one thing a lot of people, especially soldiers, do not; Krates is lucky, some god somewhere either loves or is much amused in their torment of him. He will just happen to be in exactly the place he needs to be in order to do exactly what no-one else would survive doing.
It is joked Alexander got him in the Silver and Black as a kind of lucky charm, a good omen to help his new brothers. Acora will, not entirely seriously quip that this is why he needs Krates now.
Krates has been heard to mutter that luck was better in the old days too...