Both Sasuke and Madara's Sharingan awakened/evolved after they

Strongest Mangekyou Sharingan in Naruto Ranked: Sasuke Uchiha, Indra Otsutsuki & More

Who has the Eternal Mangekyo Sharingan?

Naruto : 5 Forgotten Facts About the Sharingan, by Septionime

Kaguya Ōtsutsuki Strikes, Narutopedia

What If Itachi Got The Eternal Mangekyo Sharingan In Naruto?

What If Sasuke Joined Madara? Naruto & Minato vs Sasuke & Itachi! 80K Subscriber Q & A!

Is the Sharingan destined to die out? With sasuke and sarada only being the ones left, eventually the sarada line with dilute? Unless sasuke gets hoes? : r/Naruto

Evolution of the Sharingan and Other Eyes: Naruto Shippuuden

Evolution of the Sharingan and Other Eyes: Naruto Shippuuden

Who has the Eternal Mangekyo Sharingan?

Which Sharingan Does Itachi Have? & 9 Other Questions About His Dojutsu, Answered

naruto - Did the writer mention that 2 Tomoe Sharingan can instantly awaken into Mangekyou Sharingan? - Anime & Manga Stack Exchange

If Madara lost the use of one Sharingan after using Izanagi after his death, how could he awaken and use the Rinnegan in both his eyes later? - Quora

Both Sasuke and Madara's Sharingan awakened/evolved after they broke their bond with their best friends. I love this parallel. : r/Naruto