The House of Hades (Heroes of Olympus Book 4)

because he had Artemis’s cold eyes and Apollo’s smile. The Titan was their grandfather, Leto’s father. The idea gave Percy a migraine.
    ‘Well! I’ll see you in the mortal world!’ Koios chest-bumped Bob, almost knocking the cat off his head. ‘Oh, and our two
other
brothers are guarding this side of the Doors, so you’ll see them soon enough!’
    ‘I will?’
    ‘Count on it!’ Koios lumbered off, almost knocking over Percy and Annabeth as they scrambled out of his way.
    Before the crowd of monsters could fill the empty space, Percy motioned for Bob to lean in.
    ‘You okay, big guy?’ Percy whispered.
    Bob frowned. ‘I do not know. In all this –’ he gestured around them – ‘what is the meaning of
okay
?’
    Fair point
, Percy thought.
    Annabeth peered towards the Doors of Death, though the crowd of monsters blocked them from view. ‘Did I hear correctly? Two more Titans guarding our exit? That’s not good.’
    Percy looked at Bob. The Titan’s distant expression worried him.
    ‘Do you remember Koios?’ he asked gently. ‘All that stuff he was talking about?’
    Bob gripped his broom. ‘When he told it, I remembered. He handed me my past like … like a spear. But I do not know if I should take it. Is it still mine, if I do not want it?’
    ‘No,’ Annabeth said firmly. ‘Bob, you’re different now. You’re
better
.’
    The kitten jumped off Bob’s head. He circled the Titan’s feet, bumping his head against the Titan’s trouser cuffs. Bob didn’t seem to notice.
    Percy wished he could be as certain as Annabeth. He wished he could tell Bob with absolute confidence that he should forget about his past.
    But Percy understood Bob’s confusion. He rememberedthe day he’d opened his eyes at the Wolf House in California, his memory wiped clean by Hera. If somebody had been waiting for Percy when he first woke up, if they’d convinced Percy that his name was Bob and he was a friend of the Titans and the giants … would Percy have believed it? Would he have felt betrayed once he found out his true identity?
    This is different
, he told himself.
We’re the good guys.
    But were they? Percy had left Bob in Hades’s palace, at the mercy of a new master who hated him. Percy didn’t feel like he had much right to tell Bob what to do now – even if their lives depended on it.
    ‘I think you can choose, Bob,’ Percy ventured. ‘Take the parts of Iapetus’s past that you want to keep. Leave the rest. Your future is what matters.’
    ‘Future …’ Bob mused. ‘That is a mortal concept. I am not meant to change, Percy Friend.’ He gazed around him at the horde of monsters. ‘We are the same … forever.’
    ‘If you were the same,’ Percy said, ‘Annabeth and I would be dead already. Maybe we weren’t meant to be friends, but we
are
. You’ve been the best friend we could ask for.’
    Bob’s silver eyes looked darker than usual. He held out his hand, and Small Bob the kitten jumped into it. The Titan rose to his full height. ‘Let us go, then, friends. Not much further.’
    Stomping on Tartarus’s heart wasn’t nearly as much fun as it sounded.
    The purplish ground was slippery and constantly pulsing. It looked flat from a distance, but up close it was made of foldsand ridges that got harder to navigate the further they walked. Gnarled lumps of red arteries and blue veins gave Percy some footholds when he had to climb, but the going was slow.
    And, of course, the monsters were everywhere. Packs of hellhounds prowled the plains, baying and snarling and attacking any monster that dropped its guard.
Arai
wheeled overhead on leathery wings, making ghastly dark silhouettes in the poison clouds.
    Percy stumbled. His hand touched a red artery, and a tingling sensation went up his arm. ‘There’s water in here,’ he said. ‘Actual water.’
    Bob grunted. ‘One of the five rivers. His blood.’
    ‘His blood?’ Annabeth stepped away from the nearest clump of veins. ‘I knew the Underworld rivers all emptied into Tartarus, but –’
    ‘Yes,’ Bob agreed. ‘They all flow through his heart.’
    Percy traced his hand across a web of capillaries. Was the water of the Styx flowing beneath his fingers, or maybe the Lethe? If one of those veins popped when he stepped on it … Percy shuddered. He realized he was taking a stroll across the most dangerous circulatory system in the universe.
    ‘We should hurry,’ Annabeth said. ‘If we can’t …’
    Her voice