The latest trailer for Assassin’s Creed hints that a key part of the original video game series could become a vital part of Michael Fassbender’s story: the Bleeding Effect.

The trailer shows more of Callum Lynch’s interactions with the Animus, a device used to access the memories of his ancestor Aguilar through his genetic code. We already knew that the Animus in the movie would be more interactive than the video game counterpart, given the fact that Callum is literally reenacting the memories. But it looks like those memories and skills are sticking around, too.

For those who don’t know, the Bleeding Effect was something majorly established in Assassin’s Creed II. In the game, Desmond Miles is able to retain the fighting skills of Ezio Auditore through prolonged use of the Animus. The downside is there’s a risk that reality and memory can merge. Desmond starts seeing echoes of his memories in his everyday life, and his predecessor, Subject 16, was driven insane by the same effect.

The new trailer shows that Callum can throw a decent punch before he’s even brought into Abstergo, but it’s doubtful he knew how to do many of the things his ancestor could, like archery. However, that’s we see him do by the end of the trailer, without the assistance of the Animus. You can say he simply learned how to do it while reenacting Aguilar’s life, but the Animus was clearly guiding him through every step, using his body like a puppet. How much of that could be really be learned without the Bleeding Effect coming into play? That’s still unclear.

We also see a bleedover-style Aguilar fighting in modern Abstergo, showing that Aguilar isn’t staying put in Callum’s memory. That could hint at the Bleeding Effect taking a mental toll on Callum, blending his consciousness with Aguilar’s to dangerous levels. Or it’s just a cool special effect that won’t mean anything. Let’s hope it’s the former.

Assassin’s Creed comes out Dec. 21.