'Arrow' Star Stephen Amell: Oliver Thinks Slade Is a Good Person

Oliver and Slade's trip to Kasnia to find Slade's son continued tonight on Arrow, but the family reunion didn't go quite as planned.

Spoiler's for tonight's episode of Arrow, "Promises Kept," below!

In tonight's episode, Oliver Queen (Stephen Amell) found himself in danger at the wrong end of Slade Wilson/Deathstroke's (Manu Bennett) blade at Joe's urging. However, in spite of this -- and every other terrible thing that Slade has done to Oliver and the peole he loves over the years, including killing his mother -- Oliver still has a complex relationship with the mercenary. According to Amell, it's because Oliver thinks there is good in Slade.

In a recent visit to the Arrow seat in Vancouver, Amell told ComicBook.com that Oliver understands that many of Slade's past sins were a result of him being under the influence of mirakuru.

"Manu and I work on where they are," he said. "I thought the early drafts of the script almost slipped them back into what you would have seen in the season one, the latter part of season one, or maybe even the early part of season two back on the island. Oliver understands perfectly well that Slade was under the influence of something. He was not of his right mind."

In Slade's previous appearance on Arrow, he was under the influence of the drug mirakuru, a Japanese super-soldier serum from World War II that resulted in enhanced physical abilities, but also had the side effect of driving the user insane with aggression and hostility, even to the point of warping their mind. Slade is far more stable now that his body is free of the drug, something that leads Oliver to trust him, even though Amell says some things in the past can't be forgiven.

"With that being said, certain things cannot be undone," Amell said. "Ever. So, I really wanted to make ... DO I trust him when he is of his right mind? Yes. Do I rely on him? Sure. Are we going for a beer after our road trip to go find his son? Probably no. Probably not. There are certain things I cannot forgive. I think that at his core, Oliver thinks that Slade is a good person."

Arrow airs on Thursdays at 9/8c on The CW.