User blog comment:Master Sima Yi/Assassinews 03-03-'13 — Assassin's Creed IV: Black Flag trailer and screenshots/@comment-4705174-20130305000524/@comment-4829046-20130305162638

When? When is it ever implied they are friends? They could be comrades-in-arms or rivals or simply on a need-to-know-basis relationship like Connor and the Colonial leaders.