If you set git config user.initials to the same value as git-together.active, then bash-it's theming will pick up the current pair initials the same way it does for git-pair.
Relevant line in the bash-it profile sauce
https://github.com/Bash-it/bash-it/blob/2a0a425334af899a6fe0004f405927a6ef683f07/themes/base.theme.bash#L410
What it looks like when you set it with bash-it:

If you set git config user.initials to the same value as git-together.active, then bash-it's theming will pick up the current pair initials the same way it does for git-pair.
Relevant line in the bash-it profile sauce
https://github.com/Bash-it/bash-it/blob/2a0a425334af899a6fe0004f405927a6ef683f07/themes/base.theme.bash#L410
What it looks like when you set it with bash-it: