The foundation for the entire discussion is laid in Shemot 25:18–22, where the Torah commands that the two cherubim be fashioned with wings spread above and faces turned toward one another and toward the kapporet, and that it is precisely from between the two cherubim that God will speak with Moshe — making that space the locus of divine revelation.
The Gemara in Yoma 54a–54b reports that on the pilgrimage festivals the priests would draw back the curtain and show the people the cherubim clinging to one another, declaring: 'See how beloved you are before the Omnipresent — as the love of male and female'; and Bava Batra 99a records the dispute between Rabbi Yochanan and Rabbi Elazar over whether the cherubim faced each other or faced the House, resolving it by teaching that their orientation changed miraculously in reflection of Israel's relationship with God — facing one another when Israel did His will, and turning away when they did not.
The Nefesh HaChayim makes this dynamic explicit: Nefesh HaChayim, Gate I 8:10 explains that one cherub alludes to God and the other to Israel, and that the degree of the cherubim's closeness or estrangement — whether face to face, slightly angled, or fully turned away — was a miraculous, immediate indicator of the degree of Israel's attachment or distance from the Divine.
The Ramban on Ramban (Shemot 25:21) explains that the cherubim together with the kapporet form a single unit serving as the throne of glory upon which the Shekhinah dwells, and it is for this reason that God declares He will meet Moshe there and speak from between the two cherubim above the Ark of the testimony.
The Malbim, drawing on the Zohar and the Pardes, articulates the sod dimension: Malbim (Shemot 25:8) teaches that the cherubim represent Tiferet and Malkhut — Torah she-bikhtav and Torah she-be'al peh respectively — and that the divine word descends from the world of Atzilut through the cherubim, through the screen (masakh) that separates Atzilut from the world of Beriah, and arrives at the Throne (Kise), which corresponds to the Holy of Holies and the Ark.
The Kli Yakar on Kli Yakar (Shemot 25:17) adds that the kapporet itself signals that the secrets of the Torah must be covered and not disclosed to the masses, citing 'It is the glory of God to conceal a matter' (Mishlei 25:2), while the cherubim in the likeness of children teach that Torah may only be sought from a teacher who is both pure as an angel and innocent as a small child.
The Sforno on Sforno (Shemot 25:22) extends the principle beyond the Mishkan: the Shekhinah rested between the cherubim there, but it rests in every place where the sages of the generation are engaged in understanding and knowing God, as the Sages themselves testified that while expounding the Ma'aseh Merkavah the Shekhinah was with them and ministering angels accompanied them.
Tzitz Eliezer (9:44) rules that the cherubim are attached to and joined with the kapporet with their faces turned downward toward it, signifying their submission and servitude to those who bear the Torah resting within the Ark beneath them.