 He was probably the son of Gilbert, Count of the Maasgau, and a daughter of Lothair I whose name is not known (Hiltrude, Bertha, Irmgard, and Gisela are candidate names).In an 877 charter in the Capitulary of Quierzy, he possibly already appears as "Rainerus", alongside his probable father as one of the regents of the kingdom during Charles the Bald's absence on campaign in Italy.He was Lay Abbot of important Abbeys stretching from the Maas to the Moselle through the Ardennes, Saint-Servais in Maastricht, Echternach, Stavelot-Malmedy, and Saint-Maximin in Triers.