A/N: double update today because chapters 7 and 8 are meant to be read in one go :)
Sakumo clicks his tongue in frustration as he closes his eyes and concentrates on his surroundings again. The bright white spark of Kakashi's chakra has long since faded past the periphery of his senses — senses, Sakumo muses mournfully, which have been dulled significantly. His chakra (or whatever ethereal version of it) flows so sluggishly through his coils that he finds himself near unable to use it.
Neither is Sakumo's bloodhound nose of any help, since Kakashi knows first-hand how dangerous it can be to not mask one's scent. Crossing his arms across his chest, Sakumo scowls at the browned leaves littering the forest floor. He is lost. For one of the best trackers of his generation, this is utterly humiliating.
It is the sudden spike of Kakashi's chakra in the distance that snaps Sakumo out of his dejection and sends the cogs of his mind spinning. The flickering pulses are far away enough that it would take several minutes to arrive even at a proper jounin-speed sprint. He quickly decides on a long range shunshin, even though it may take some effort to wrestle his strangely viscous chakra into compliance.
His hands flash through the jutsu's series of seals as he pinpoints the location in his mind. Mentally drawing a bright line from himself to Kakashi's bursts of chakra, he forces his chakra through his body and—
Sakumo appears within a small bamboo grove only to get nailed by Minato's kunai straight between the eyes, making him yelp and duck instinctively though he remains completely unharmed. Unfortunately the shinobi behind him cannot say the same — he collapses dead with a small spurt of blood.
Wincing at the memory of the kunai's phantom tug as it slipped through his brains, Sakumo hurries out of Minato's much-too-graceful brawl. The small clearing is wrecked. Minato's uniquely marked Hiraishin kunais are strewn across the torn up earth, bright specks of white and silver against the mud-brown of trampled grass. Dead bodies bearing the Iwa hitai-ate are littered about almost carelessly as Minato flits about, picking off the remaining few fighters with deadly accuracy.
Sakumo turns away from the massacre, anxious to confirm the kids' safety. The sight of Kakashi and Rin half-hidden behind a large boulder prompts a grateful sigh of relief but a second look makes him still.
Crouching behind Kakashi, Rin seems just this side of chakra depleted, the purple stripes on her cheek stark against her pallid skin. She will be alright, but Kakashi—
Kakashi has a Sharingan. A single Sharingan that is his left eye, framed by a violent line of red gouging from his eyebrow to the nicked edge of his mask. His eye could have never survived that injury.
The uncomfortable feeling in his chest solidifies into a ball of lead as a sickening realisation dawns upon Sakumo.
Obito is dead.
Rin would have never transplanted Obito's eye into Kakashi unless Obito was gone.
Grief hits Sakumo with an unexpected intensity. For all the death he has experienced, many of them family, friends and comrades, the initial blow of knowing that someone is gone forever never managed to soften. In spite of the fact that Sakumo had only known the boy for a few months and Obito never even knew him in return, Obito had somehow become a child he cared deeply about, just as he did Kakashi.
Yet... Obito is dead.