Held captive by Anthony Ivo on the Amazo and meeting Oliver Queen (Stephen Amell) there, Anatoly Knyazev (David Nykl) formed a close bond with the future Green Arrow. That all looks set to change with 'Arrow' season 6 however, as the former friend is making a comeback, but proving to be a troublesome adversary for the skilled archer.

Stephen Amell will return as the Green Arrow in 'Arrow' season 6Stephen Amell will return as the Green Arrow in 'Arrow' season 6

Having slipped into the criminal underworld, serving only himself and hoping to further his power whenever possible, Anatoly is now a corrupted man with a heavy cross to bear. Exactly how Oliver will deal with his return remains to be seen, but it's going to be very interesting to see how their past relationship plays into the upcoming scenes in season 6.

Speaking with EW, Amell explained: "Anatoly has an interesting power over him [Oliver] that I don't know a lot of other villains - if any villain at all - has ever had.

"Oliver didn't kill Chase for a very specific reason, because that's what Chase wanted, but he tried to kill Malcolm, and he killed Slade once upon a time, and then put him away in prison, and then he went on this anti-killing thing, but he still killed Ra's al Ghul and still killed Damien Darhk. Anatoly is this weird grey area of a guy that he loves and respects too much."

This level of respect is something that could cloud Oliver's judgement when going up against Anatoly. Though he's somebody that the hero has loved in the past, he needs to realise that he's no longer that same man if he's to successfully work a plan in taking him down. With the survival of Team Arrow on the line, he'll hopefully be able to put the working relationships he's formed more recently ahead of the ghosts of his past. If not, we could see a lot of repercussions from his actions this season.

More: Stephen Amell Wants Funnier 'Arrow' In Season 6

'Arrow' season 6 premieres on The CW in the US on Thursday, October 12 and is expected to debut on Sky 1 in the UK shortly after.