Assuming skill proficiency is also added, this can easily result in bonuses of 12+ (without expertise)
I would say only one proficiency should be added ...
Cant explain it tho, but it kinda doesnt seems right to add the same bonus twice.
So unless you're arguing for the DCs of checks to be increased by 5 across the board...?
Actualy ... i do, in some sort of way.
I mean, the outcome you described would be possible in DnD, where people can react on each other in real time ... here we have predetermined dice rolls, and anything beyond those prepared options is litteraly impossible (i dont count mods, since they only make our list of options wider).
So aswell as Wyll will (i just love this) never be able to roll to Intimidation in middle of Tavs conversation (like Tav is the one who is talking not Wyll) ... OR vice versa ... unless Larian specificly imlpement to that specific dialogue at least single option for us to use Wyll to resolve this situation.
Aswell as We will never be able to use our alternative Ability scores, unless Larian specificly give us additional Diceroll option with alternative Ability score (or implement option to add it as a bonus) ...
The same we would never be able to use two characters Ability score to roll dices within single dialogue.
Therefore IF someone in Larian would like it, and gived us this option ... he can easily incerase Difficiulty option for that specific roll.
You know like:
Tav [Intimidation] > Dif 15
Tav + Lae'zel [Intimidation] > Dif 20
Yes im aware that it would negate whole effect from mechanical point of view.
And yes im aware that people would find out pretty fast, IF they would save scuming. :P
But it would look better in my honest opinion, in conversations.
I simply adore that part when my Drow Tav was helping Lae'zel to interrogate Zoru ... Lae'zel was being intimidating, and my Tav was just staring at him as evil as she could ... and it worked like a charm. I simply want more options to use our companions like this. ^_^
I think what you want can be accomplished by other options. The 5e "Help" action, where an ally can help another to gain advantage on the roll. In this case, Wyll would roll his Cha (Intimidation) at Advantage or Lae'zel would roll her Strength (Intimidation) at Advantage.
Advantage was my first idea to be honest ...
But concidering that most people was against advantage in other cases, and wanted rather flat bonus ... wich by the way showed to be great solution ... i presumed this would be simmilar.
Also, there are allready things to give you advantage during conversations ... and i didnt want to diminish them.
Or each of them would roll their own ability and you'd take the higher.
This is great idea!
I love it. :3
Importantly, both of them would participate in the dialoge/cutscene.
Additionally, the "party should feel like a party" goal can be met by other party members speaking up & expressing their opinions in dialogue without Tav/the speaker specifically asking them. I.e., them not meekly standing there in silence for most of the time.
This both should go without saying ... i mean there clearly is progress, but it would need much more.