Gemini · Sagittarius
One of you collects the questions. One of you already has the answer.
Gemini and Sagittarius sit opposite, and both are mutable, which means neither of them is the one holding this in place. Gemini gathers, endlessly, and commits to nothing. Sagittarius arrives at a conclusion early and will defend it at dinner. They will talk for years. Whether they stay is a separate question.
What pulls
The conversation, immediately and for a long time. Gemini finds someone who does not get bored and does not ask them to be consistent. Sagittarius finds someone who is genuinely curious rather than politely waiting to speak. Neither of them has ever been the restless one in a relationship before, and the relief of not being the difficult one is enormous.
Where it grinds
Sagittarius states things as fact. Gemini, who can argue any side and means none of them permanently, finds this crude, and says so, usually by taking the opposite position for sport. Sagittarius experiences that as slipperiness and asks what Gemini actually believes, which is the one question Gemini finds genuinely difficult. Then Sagittarius calls it evasion and Gemini calls it thinking, and both are partly right.
The long version
Two mutable signs means there is no ballast here. Nothing is holding the two of you in place except continuing to want to be, which is either the lightest thing about this pairing or the most precarious, depending on the week. It rarely ends in a fight. It ends in drift. Whether it drifts depends almost entirely on Saturn, and Saturn is not a thing a Sun sign can tell you about.