Help! Bonding scared rat

[Juste]

Hey, so my boy ~2yo (Pepper) lost his cage mate, i adopted another rat~1,5yo (Remy) and today was the first intro.. it was so much easier with girls, i kinda regret now that i adopter a boy.
I did put them in a bathtub, Pepper was afraid of Remy. He just froze in one spot and didn't even sniff him, didn't want to interact at all. Remy was all over him and they got into a bit of scuffle, nothing too serious just a bit of fur was flying. After that Remy was calmer, but a lot of teeth chattering. Once again Pepper was frozen in one spot. And when again Remy was trying to show dominance, Pepper tried to get away from him and run away out of the bathtub.
How do i do intros when Pepper is so scared of Remy?

 

[Evermore]

For a few days, set their cages side-by-side (but far enough apart they cannot reach each other) so they get accustomed to one another's presence and scents. Once a day, or once every other day, swap a blanket or hammock from each cage into the other. Don't bother with the neutral bathtub again for at least a week; let them both acclimate. This is a new home for Remy, and a new friend for Pepper. Even if they are side-by-side in separate cages, that is still socialization.

When you are ready to attempt the bathtub again, dab some vanilla extract at the bases of their tails or the backs of their shoulders (just a bit). This is incentive to interact, and [sometimes] encourages mutual grooming because vanilla is delicious.

 

[Juste]

For a few days, set their cages side-by-side (but far enough apart they cannot reach each other) so they get accustomed to one another's presence and scents. Once a day, or once every other day, swap a blanket or hammock from each cage into the other. Don't bother with the neutral bathtub again for at least a week; let them both acclimate. This is a new home for Remy, and a new friend for Pepper. Even if they are side-by-side in separate cages, that is still socialization.

When you are ready to attempt the bathtub again, dab some vanilla extract at the bases of their tails or the backs of their shoulders (just a bit). This is incentive to interact, and [sometimes] encourages mutual grooming because vanilla is delicious.

Thank you so much for your reply. I really want this to work out. The woman at the rescue said that if they don't get along i can always bring Remy back.. but he's so sweet, kinda reminds me of Peppers brother that we lost recently.