I sent this to @mage-of-homestuck as a series of asks earlier today, but I feel like it’s worth its own post here for posterity’s sake.

The letters B and O are of particular importance in Homestuck, particularly in that sequence, BO.

It’s those two letters that get quirked in the word sym69ls; B is also quirked as the number 8, whose significance to the story is obvious. The letter O appears in the names Doc Scratch, Snowman and Lord English, and is rendered in a special way in all 3 of them - white, black, and flashing pool ball style, respectively, signifying the letter O representing pool balls. The letter O is also associated with the number 0, like in Aradia’s quirk which forms part of the t1ck / t0ck binary.

By forming the numbers 6 and 9, B and O make up the two halves of a double ouroboros, forming a duality between the two characters. This duality manifests in a few ways.

The phrase ‘Alpha and Omega,’ from the first and last letters of the Greek alphabet, means ‘beginning and end,’ and was popularised by a line in the bible describing God’s eternal existence. B and O make ‘Beta and Omega’ instead, which is particularly relevant to Homestuck because the comic began with a Beta rather than an Alpha. It also connects to the idea of Lord English as God, because English couldn’t enter the Trolls’ universe until they scratched, meaning he skipped the Alpha phase and began at the Beta phase.

With O as zero and B as eight, and eight representing an infinity, O and B can also represent ‘nothing’ and ‘everything’. With the letter O representing Doc Scratch (who is also member number 0 of the Felt) during his Intermission and the number 8 representing Snowman, the letters are also connected with white and black, as well as creation and destruction.

It might also be worth bringing up that O and B are prominent letters in the word ouroboros itself (though not so much in Homestuck’s own rendering of the word, ‘uroburos’). They also appear together in the name Caliborn, which might have something to do with the sym69ls themselves, given that speaking the name appears to have a power of its own.