"He was a big man, and not just physically; everything about his panoply of affectations, the ragged straw hat, the long, flowing mantle that was almost, but not quite, a sea coat, the purposefully untrimmed fringe beard, said that this was a man who was constantly outside of himself. His eyes were the shade of clear sapphire blue that people often used to depict the ocean in paintings, and had a slightly crazy gleam. His clothes, in contrast to the trappings surrounding them, were relatively modest; open linen shirt, a sash belt around his waist (into which was tucked a flintlock) and fine black pants that stopped mid-calve, leaving sandal-clad feet unencumbered. He stood shipboard, on the lee side of the yardarm, with the wind blowing his mantle so as to almost fully conceal the left side of his body; there was the hint of a longsword beneath it."
Shanks was born in 1292, shortly after the Annadil Crisis, to Ynell Star, Princess of Rebma. His father was Lord Mihawk 'Eagle-Eyes' Darios, youngest son of Ahab and Igdi. He is illegitimate; his mother had a long-standing and warm relationship with House Darios, who sponsored her walk through the Logrus, but Queen Moire was somewhat cooler, not entirely sure she wanted Rebma tied too closely to an at-the-time distant, alien power.
Shanks stands well down in the order of succession, and was considered to be something of a cripple in his younger years by much of the rest of House Darios, as he had absolutly no ability to shapeshift whatsoever, and displayed little aptitude for other powers. His natural physical abilities were considered somewhat impressive (well above the norm of a Lord of Chaos of comparable age) and he found a productive role being the liaison between his mothers organization, Bloc Rebmaquois, and House Darios, which heavily funded and supplied the Bloc in its formative years.
Shanks served briefly in the Red Fleet during the Herald Crisis, fighting the Wu-fleets. Relations berween him and his grandfather became more strained after that, as the repeated humiliations heaped upon House Darios during the Herald Crisis, especially their betrayal by House Helgram, had, in Shanks' opinion, turned Ahab into a bitter, irrational ball of vengeance ruled by his emotions. Shanks, in turn, was regarded as something of a milquetoast weakling by both Ahab and a large number of his relatives, many of whom thought less of him because he regarded the task of smashing into Amber and freeing his mother from stir as hopeless. The entire Igdi/Ilin?/Mina? incident reinforced Shanks' opinion of his grandfather.
Mihawk largely shared the opinions of his son, but as one of the more junior sons, and a naturally restrained man, he largely viewed it as not his place to voice an opinion, and concentrated on quietly building up his own power base and to encourage Shanks to do the same.