The actress told the Los Angeles Times that the pair's relationship will begin to change during the Thanksgiving episode.
"[The other characters] actually really like Zoey, which is what makes Ted really mad because we end up all having this great, fun night together," she said. "And Ted's like, 'But she's my enemy! You can't be friends with my enemy!'"
She continued: "Definitely more [common ground] grows by the end of the Thanksgiving episode. It's a definite slow burn. The audience is going to get little pieces of information about Zoey very slowly. There's not huge things that come out. There's not a bunch of things that all come out at once. It's sort of like each episode you get another piece of the puzzle, figuring out who she is and what she means to Ted."
Morrison also hinted that the Thanksgiving episode will see the pair return to their original friendship.
"When they first meet, they obviously have chemistry," she said. "They obviously like each other and have a lot in common. It isn't until the building issue starts that they are in conflict. [In the episode], it's the first time that we return to that feeling between them where there's some sort of truce at least for the moment, for the holiday, and realising they do have a lot in common. It'll be interesting to see how they maintain conflict after we get to that place of starting to see eye-to-eye a little."
How I Met Your Mother continues on Mondays at 8/7c on CBS.