Fringe was a true mind-bending series, pushing the limits of storytelling, yet always trusting that its audience would keep pace. It dared the viewer to keep investing in the series, finding new and thrilling ways to stretch the boundaries of the genre. Peter flung the door wide open on what Fringe was about and what it was hoping to be with the simple question: What wouldnt you do to save the life of your child? Yet the child isnt actually your child, but the child of your alternate-universe self. Answering questions the series had already laid out, Peter accomplished the task of fully realising the complex relationship between father Walter (an Emmy-caliber performance by John Noble) and son Peter (Joshua Jackson). The fact that his own son had died in the prime-universe drives Walter to save the life of the parallel-universe version of Peter. The realisation that the Peter viewers had been seeing up to this point wasn't the real Peter is stunning. It drives home the extent to which the characters were willing to break the rules and the risks the series would take in weaving a complex tale. From its 80s-style title sequence to its poignant final moments, Peter is a fantastic episode from an awesome series.