Complex sentence: Throughout 2008--09, Pernía remained first-choice most of the campaign; surprisingly, he saw the birth of his own official fanclub- "Peña Pernía", which was Atlético's fastest growing "peña" of 2008.
Split into simpler sentences: Throughout 2008--09, Pernía remained first-choice most of the campaign. He also saw the birth of his own official fanclub- "Peña Pernía", which was Atlético's fastest growing "peña" of 2008.