Erasmus Tycho was the Captain of the Blood Angels 3rd Company who participated in both the Second and Third Wars for Armageddon. He is a shining example of Your dudes, as his background came from the very first White Dwarf battle report for WH40K Second Edition where he was killed by an Ork player's Weirdboy. His official name and wargear are the same as they were in that first battle.
By the time of the Second War for Armaggedon, Tycho was the Veteran Sergeant of the 3rd Company's Command Squad, and quickly took charge when his predecessor was killed early in the fighting, and Chapter Master Dante soon confirmed his appointment as Captain. However, the battle saw Tycho's face suffer nerve damage, leaving him with a rictus grin. Like any self-respecting son of Sanguinius, Tycho had an appreciation of beauty, and was unable to keep looking at his injured face. Now that he was a Captain, he had a golden face cover placed over the right side of his face. Tycho's hatred for the Orks was great, and after brooding and sulking on Baal for a while, he began volunteering for dangerous missions against the Orks. His victories earned the admiration of the Blood Angels rank and file, and there was talk that he would succeed Dante as Chapter Master. However, the Chaplains were growing concerned over the anger that was festering in him. When the Third War for Armageddon came, Tycho volunteered the Third Company for deployment. During the War, Tycho began to have visions of Horus, and Chaplain Vermento inducted Tycho into the Death Company. He spent his last battle taking an Ork-held hive city, during which he was a instrumental participant.
On the Tabletop
Tycho actually has two profiles, meant to represent him before and after his fall from grace.
|Tycho the Lost:||70||6"||2+||2+||4||4||5||4||10||2+/4++|
Captain Tycho is a ranged-geared captain with ATSKNF, Rites of Battle (OR the Black Rage if you take his edgy version), Abhor the Beast(Orks), and his warlord trait "Selfless Valour" increaes his Heroic Interventions to 6". He takes to the battlefield with artificer armor, an iron halo, a bolt pistol, frag and krak grenades, Dead Man's Hand, and a relic combi-weapon: the Blood Song - basically master-crafted boltgun strapped to a meltagun. Tycho is a bit of an oddity. In an army as devoted to SMITE AND CLEAVE as the Blood Angels, he's a captain with a S:User, -2 AP, D1 melee weapon. Obviously you should stick him in a squad of sternguard, where he'll do a fine job. He's fairly cheap for a captain, but you're spending 70-85 points for a melee-oriented sternguard equivalent with sub-par melee performance. Read as: Shit.
Tycho's name is probably inspired from the danish astronomer Tycho Brahe, who had his nose cut off in a duel and replaced with one of silver (like Tycho and his mask). His first name: Erasmus is basically just an archaic given name that rarely gets used in western English but has been used by several historical figures (most notably Erasmus of Rotterdam, the Dutch Renaissance humanist scholar whose biblical translations strongly influenced the Protestant Reformation).
Come on, he was a filler character for an early white dwarf battle report who became a permanent character, it's not really going to be deep and meaningful, though Erasmus does derive from the ancient greek Erasmios for "pleasant" so can refer to Tycho's pretty face.
VERY unlikely theory
As Erasmus Tycho is partially named after a Dane, it is possible that the name "Erasmus" comes from a famous Danish stage-play, called "Erasmus Montanus". It centers around the homecoming of peasent Rasmus Berg, who was sent to the university of Copenhagen in the early 1900s to educate himself into Latin and the world in general. When he arrives at his birthhome, he had his name changed to Erasmus Montanus, believing it to be the Latin version of his name ("berg" being a mispelling of "bjerg", the danish word for "mountain", and "montanus" being Latin for the same.), and generally being a ponce about his newfound knowledge. As it turns out, he has learned a lot of stuff, but doesn't have a clue as to how to apply it, and uses faulty logic to argue his cases (A famous example being him turning his mother into a stone, by ascerning, that "A stone can't fly, mom can't fly, so mom must be a stone", alienating anyone and making his mother cry. This way of arguing is, to this day, called "Montanish Arguement" in Denmark), and ending up being forced to give up his knowledge by agreeing that the world indeed is flat, and not round, as he stated.
What this says about Erasmus Tycho, being named after a great and a lousy scholar respectively, while himself having two different sides (the noble one and the mad one), is up to you.