1025

1025 is the third significant number to make an appearance in Homestuck. It is the result of adding 413 to 612 and thus is symbolic of the interconnection between the kids' and the trolls' sessions, as well as the Green Sun.

Appearances as a Time[]

Jade's countdown, instead of being a variation of 413 like the other kids, is 10:25 instead . This connects to Jade's Guardian, Becquerel, also being a first guardian, and Jade's eventual merge with him. Jade also notes how these kinds of numbers are often significant.
A timer begins counting down when Jack Noir appears in the trolls' session which starts at 10:25 when he slices the door to the kids' universe.
Karkat wakes from dreaming at 5:12:30 according to the timer. 5:12:30 is half of 10:25:00.
The Tumor contains a counter inside the center dot that starts at 10:25 when first seen.

Appearances as a Date[]

In Hiveswap one of Joey's diary entries is dated 10/25/1994, in the entry she laments her return to school and is surprised that she hadn't made a diary entry since the beginning of the school break on 6/12.
The trailer for Hiveswap: Act 2 was uploaded on October 25, 2020.

Appearances as a Random Number[]

In the ministrife , Equius calls out Aradiabot #100502, which contains the digits 1, 0, 2 and 5, as well as Equius' associated number 100.
In the Credits, it is the streak number Dave has with John's Snapchat.

Appearances related to the Acts[]

The Alterniabound flash was posted on October 25, 2010 (10/25).
Cascade was released on 10/25/11, exactly 2 years, 6 months and 12 days after 4/13/09, when Homestuck began, and also 1 year, 4 months, and 13 days after 6/12/10, when Hivebent began. The time of posting was 12:50.
GAME OVER was released on 10/25/14. Act 6 Act 6 Intermission 3 was posted in full later that same day.
The Homestuck credits were released on 10/25/16.
Homestuck: Book 3 was scheduled to be released on 10/25/18.
On October 25, 2018, musician James Roach posted a selfie of Andrew Hussie and a screenshot reconfirming Homestuck's epilogue being in the works.
Homestuck^2: Beyond Canon was announced and released on October 25, 2019.

Appearances related to the Songs[]

The albums "Homestuck Vol. 6: Heir Transparent", "Homestuck Vol. 7: At the Price of Oblivion", "Homestuck Vol. 8", and "Homestuck Vol. 10" all cost $10.25. Vol. 8 was also released on October 25, 2011 and Vol. 10 has 25 songs in it.
The song "Clockwork ♫" in the album "Medium" is 5:13 long, while the song "Heat ♫" from the same album is 5:12 long (512+513 = 1025).