Claire's death was a mystery - why did she succumb to heart failure during childbirth, being possessed, as she was, of profound regenerative powers? Turns out one of her twin babies, Nathan/Tommy, has the power to take the power from a proximate hero/evo, and so inadvertently robbed Claire of the ability she needed to reverse the heart attack's damage. That's a pretty good if tragic twist.
And why did Nathan/Tommy, raised in the protected past by Hiro - whom he now considers his father - not know any of this in the Heroes Reborn story so far? That answer was also good, and hiding in plain sight in front of us all along: the "penny for your thoughts" man, who has been protecting Tommy all along, took away all of Tommy's knowledge of Hiro etc to protect Tommy from himself, and his determination to go back in time to save Hiro and who knows what and who else.
But what did happen to Hiro, after that great scene in which he says goodbye to his son, and turns to face the clone attackers with just his swords and no super powers? He's surely not dead, though we may not see him again this season. (Molly, on the other hand, is gone, and the conversation between her and Noah, with his knowing exactly what would happen to her, was tender indeed.)
We don't have answers for lots of things yet, by any means, especially because Noah's trip to the past did indeed step on butterflies, which kicked new caterpillars into action, which will no doubt metamorph into who knows what in the weeks ahead.
See also Heroes Reborn: Good to Be Back ... Heroes Reborn 1.3: Carly Fiorina meets Steve Jobs ... Heroes Reborn 1.4: GPS RIP ... Heroes Reborn 1.6: Space, Time, Videogame ... Heroes Reborn 1.7: Time Travel and Twins
And see also Heroes Season 4 Premiere: Metaphysics, University, Carnival ...Heroes Meets The L Word in 4.5 ... Heroes 4 Mid-Season Finale ... Heroes Season 4 Resumes ... Heroes 4.15: The Chess Game Continues ... 4.16: The Trial of Hiro ... 4.18: Penultimate ... Heroes Forever
And see also reviews of Season 3 Heroes Gets Lost ... Heroes 3 Begins: Best Yet, Riddled with Time Travel and Paradox ... Sylar's Redemption and other Heroes and Villains Mergers ... Costa Nuclear ... Hearts of Gold and the Debased ... Seeing the Future Trumps Time Travel ... Superpowered Chess with Shifting Pieces ... Villains and Backstories ... The Redemption of Sylar ... Thoughts on the Eclipse, Part I ... The Lore of the Comic Book Store ... Hiro's Time Traveling Closure ... Augmented ... Shades of Recalibration ... Baby, Rebel, and Last Fantasy ... All that Shape Changes Remains the Same? ... Season 3 Finale: Hopeful Deceptions
Reviews of Season 2 Heroes: Episode 1 ... 2 ... 3 ... 4 ... 7. Heroes Meets 12 Monkeys ... 9. How Immutable Are Fate and Isaac's Futures? ... 10. Penultimate for the Fall ... Heroes 2 Finale: Heroes Who Didn't Survive
And from Season 1: Heroes in Focus ... Heroes Five Years Gone: Triumph of Time Travel and Comics ... Heroes the Hard Part: Only the Pictures Not the Words ... Heroes Landslide: Winnowing and Convergence ... Heroes Volume One Finale
If time travel is your cup of tea ...