Reno and his fear of the geostigma.
Because he couldn't remember where he'd gotten them, and besides, they didn't look like normal bruises; the dark purple/black of broken blood vessels just under the skin.
They looked like the stigma. Like the marks Rufus carried on his wrist and throat and face.
So he'd spent two days sweat bullets, making sure his shirt was completely buttoned, refusing to undress in front of Rude with the lights on. Two days of cold, gut-clenching terror, because he wasn't ready to die yet, he'd never be ready to die, and he'd already seen how the boss suffered, and he'd be damned to Tartarus if he'd put Rude through that, and he wasn't sure he could survive it himself.
He wasn't as strong as Rufus. He never had been.
Then the mission to the Northern Crater went pear-shaped, and in the ensuing confusion, he got so distracted that when he woke up one morning a week later to find the spots had faded to the sickly yellow shade common to healing bruises, he'd started crying and woken Rude up, and he couldn't explain why. All he could do was lie in Rude's arms and thank Shiva he'd been spared, and feel like shit because it had all been a false alarm.
Knowing all the while that Rufus had no such hope, and that with Tseng and Elena gone, it was up to him and Rude to take care of him now.