Question: Who is the paternal grandfather of Túathal Mac Máele-Brigte?
Answer: Bran Ardchenn

This sept had their royal seat at Maistiu (Mullaghmast) in South Kildare. He was the son of Bran Ardchenn mac Muiredaig (died 795), a previous king. He ruled from 805 to 806 and again from 808 to 818