Later, we returned to our own ship for the long flight home. I remained phased, penitent and brooding.

Kari sat back in the pilot seat and removed her helmet, shaking out her short, auburn hair. "Neko," she called, pulling off her gloves.

I phased into reality. A ghost resembles a star-shaped robot, four points around a central core with an eye in it. When I'd been repaired, she had them equip me with a blue shell with the pattern of a rampant lion across it. I looked good.

"Yes, Guardian?" I said.

She pulled off her gloves and held out her left hand. "What is this?"

A black blister the size of a hen's egg had risen on the back of her hand. Black lines spread out from it under the surface of the skin. Somehow, I had missed healing it when I had rebuilt her insides.

"Foul Hive poison," I said, tracing it with a concentrated healing beam.

Some of the discoloration faded, but the black blister remained.

In disbelief, I swept it again. Again, my healing beam had no effect.

"That grenade," Kari said. "I felt a piece of shrapnel pierce my hand. You healed me, but ... what is this?"

"I've never seen anything like it," I murmured. "I'm so sorry, Kari. I failed you again."

"These things happen," she said, waving her other hand dismissively. She pulled out her combat knife. "I'll burst this blister and let it drain. No problem."

"I don't think that's a good - "

Kari lanced the blister. Black, foul-smelling glop oozed out. She cursed and fumbled for the first aid kit under the seat, which we had never used. She wiped up the black stuff and sprayed the burst blister with antiseptic. "Now heal it."

I hit it with another healing beam. The blister flattened and smoothed over, but there was still a hint of darkness beneath the skin.

"Good enough," Kari said, and set a course for Earth.

I watched and said nothing, despite my misgivings.

I assumed that upon arriving back at the Last City, Kari would seek proper medical attention. She might have, too, given time. But we arrived home just as the Red Legion attacked the city and caged the Traveler, shutting off our Light.

This devastated Kari and nearly killed me. The source of my vitality was cut off. I barely had the strength to phase myself, let alone keep her healed properly, and there would be no speedy resurrections.

But Kari had been a soldier before she had been a Guardian. She and a bunch of others holed up in the Crucible arenas.

The Crucible was a combat sport played by Guardians. When you can resurrect after any death and heal any injury, blood sport becomes socially acceptable. Ostensibly for training Guardians, the Crucible was the main entertainment of our city, with popular teams and lots of back alley gambling.

The arenas themselves were a set of disused industrial complexes with lots of blind corners, catwalks, and deep shadows. Kari had been a top-ranking fighter at one time. She and the other teams knew every inch of the entire place.

The Cabal didn't.

Wisely, instead of making a last stand there and having the Cabal bomb it, they hid in the tunnels and secret rooms. When Legion patrols passed through, the Guardians haunted them, casting phantom lights, making noises with no apparent source, and rearranging Cabal equipment like poltergeists. I, myself, became adept at flying around with a black sheet draped over me.

The Legion soldiers grew terrified of our arenas. Their commanding officers punished them, forcing their troops to patrol, but the soldiers soon only kept to the well-lit areas.

The Guardians collected supplies and survivors into the secret places. Their goal was to build up an army and undermine the city's captors from the shadows. Therefore, when Zavala himself led a charge to retake the city, we joined in, too.

Then the miraculous happened and the Traveler awakened, slaying our enemies and healing us all in one mighty flash of Light. It was a time of miracles.

We began rebuilding the City and gathering survivors. The Tower was wrecked, so we relocated operations further down the wall, around a disused hanger.

A month slipped by, then two. In all the joyous bustle and work, Kari never remembered to have a doctor examine her hand. I confess that I forgot about the blister. She kept her gloves on most of the time and acted perfectly normal.

Then one day, Kari awakened with a fever that I couldn't heal.

She lay wrapped in blankets in her bunk, soaked with sweat, but shivering. I hovered over her anxiously. My healing beam couldn't touch this fever, not even to reduce it.

"Let me see your hand," I told her.

Kari untangled her arm from the blankets and held it out. I recoiled in horror.

The blister had become a spiderweb of black engulfing her whole hand. The nails on two fingers had turned withered and twisted-looking. I tried to heal it, but nothing happened.

"Fetch a doctor," she murmured to me.

I hesitated only a second - then I shot away through the tower, phasing through walls and obstacles, heading for the medical ward downstairs. Kari was ill. Guardians never took ill - their ghosts kept them healed. What was this awful blackness, this thing that my Light couldn't touch?

I might lose my Guardian after all.

The horror of this consumed me, driving me onward, faster and faster. I arrived at the medical ward in a babbling panic. "My Guardian - her hand - she needs help. Someone help me! I can't heal - don't know why - "

The sight of a ghost, alone and incoherent, lit a fire under the medical staff. In a few minutes, they summoned a doctor and two nurses. They followed me back upstairs. Thankfully, nobody asked questions on the way. I was too upset to navigate and talk at the same time.

I led them into Kari's room and flew to her, caressing her with a healing beam that did nothing. "It's all right now. I brought help."

She rolled her head sideways to look at them, sweat gleaming on her face. Observing how out of breath they were, she said, "I'm sorry if my ghost inconvenienced you. He gets a little excited."

"Excited!" I exclaimed. "Show them your hand! I can't heal this and I don't know what to do."

"A wound a ghost can't heal?" the doctor said, exchanging glances with his companions.

Kari held out her blackened hand.

Dead silence filled the room. The doctor and nurses stared, eyes wide. One nurse cringed backward.

"Where did you get that?" the doctor breathed.

"Hive," Kari replied. "Shrapnel wound that wasn't healed."

I shrank my facets together a little tighter. My fault.

The doctor pulled out a radio. "This is Doctor Von. I need a quarantine chamber prepared immediately. I have a patient with a level four Hive infection. Clear the hallway of all personnel and patients."

Quarantine. Level four Hive infection. Each word hit me like a hammer blow.

Kari must have read my expression. She touched me with the fingertips of her good hand. "It's not your fault."

I couldn't answer, couldn't argue. It was very much my fault, and I was entering a ghost's worst nightmare - that of being unable to save their Guardian from a final death.