Venus in the 1st house synastry means their Venus falls in your 1st house: where their affection lands in your life. What it feels like from both sides, the gift, the shadow, and how to find your overlays.
Their Venus in your 1st house puts the planet of affection and taste on the house that governs your body, your face and the way you walk into a room. They find you attractive almost immediately, and you feel more attractive around them. The classic pattern is instant liking, often mistaken for instant love.
Their Venus in your 1st house
For you, this is one of the most flattering overlays to receive. They notice your clothes, your hands, the way you laugh, and they say so. You start dressing a little better, standing a little straighter, because someone is clearly enjoying the view. Your 1st house is how you meet the world, and their Venus makes meeting the world feel easier when they are next to you. For them, you embody their idea of what is lovely. Their taste is confirmed by your appearance and manner, so being seen with you feels like wearing something they chose well. They soften around you and tend to become more charming, more polite, more generous in your presence. Friends often comment that the two of you look good together, and that comment lands on both of you.
The gift
The gift is ease. First dates, introductions and awkward reunions go smoothly because they are visibly pleased to be with you, and that pleasure is contagious. You get a mirror that reflects your best angles back, which can rebuild confidence after a period of feeling invisible. They get a partner who makes their taste look right in public. Physical affection tends to come naturally here: a hand on the arm, a hand in your hair, easy touch.
The shadow
The shadow is surface. Because attraction arrives before knowledge, both of you can skip the part where you find out who the other actually is. You may start performing the version of yourself they admire and lose track of what you wanted to wear or say. They may love the look of you more than the whole of you, and go quiet when you are tired or unglamorous. Watch for a slow makeover you did not ask for.
Working with it
Let the compliments land, then check them against your own taste. If they praise a jacket you dislike, say so and see what happens. A relationship built on this overlay grows when you show them an unpolished morning early: no make-up, bad mood, old t-shirt. If the warmth survives that, it is real affection and not just admiration. Their side of the bargain is one question about your inner life for every remark about your face.