Tamaki Souh had invited himself to Haruhi's family gathering, he was attending and was ecstatic to meet Haruhi's family and to be at his first "commoner" family gathering seeing how different it was

So there Tamaki was, introducing himself to everyone, Managing to introduce himself and make small talk with everyone especially the small kids, he walked from the backyard where everyone was gathered into the house into the kitchen noticing you cooking and watching some of the smaller kids