Short answers, pulled from the story.
The Cyrillic script is a writing system used for various languages across Eurasia. Around 250 million people use it as the official script for their national languages, with Russia accounting for about half of them. It serves Slavic, Turkic, Mongolic, Uralic, Caucasian, and Iranic-speaking countries.
The Early Cyrillic alphabet was developed during the 9th century AD at the Preslav Literary School in the First Bulgarian Empire, under Tsar Simeon I the Great. It was likely built by the disciples of the Byzantine brothers Cyril and Methodius, including Clement of Ohrid, Naum of Preslav, and Constantine of Preslav. The script is named in honor of Saint Cyril as homage rather than authorship.
The script was conceived and popularised by the followers of Cyril and Methodius in Bulgaria, rather than by Cyril and Methodius themselves. Its name denotes homage rather than authorship. Cyril and Methodius had earlier created the Glagolitic script.
In 1708 to 1710, Peter the Great heavily reformed the Cyrillic script used in Russia after his Grand Embassy in Western Europe. The new letterforms, called the Civil script, moved closer to the Latin alphabet, abolished several archaic letters, and distinguished upper and lower case. Peter designed several new letters himself.
After the Soviet Union disintegrated in 1991, Moldova, Turkmenistan, and Azerbaijan completed transitions from Cyrillic to Latin, and Kazakhstan transitioned in 2025. Uzbekistan still uses both systems. The Russian government mandates Cyrillic for all public communications in every federal subject of Russia.
Cyrillic became the third official script of the European Union in 2007, following the accession of Bulgaria. It followed the Latin and Greek alphabets.