@cheshiremachin I've mostly just read Plato's dialogues and done external research on the Christian interpretations of it. If I were to summarise the scholastic view, all things that exist derive their existence and attributes from the Good (later identified as God), and their natural end (telos) is oriented towards obtaining the maximal degree of participation in the Good according to their own natural constraints. This is interpreted as going to heaven, or Theosis if you want it to sound smart, in which the purpose of the individual is reconciliation with God, and a life of sin is one oriented away from its telos, which leads to eternal separation from God, known as Hell.
In Phaedo, Plato argued through his dialogue with Socrates that rational creatures have an innate recognition of perfection, as when we recognise that something is lacking in perfection we establish the quality it is being deprived of. His example is with sticks and stones. If we see two sticks that look almost entirely equal, yet are not exactly the same, we know that they are lacking in the highest degree of equality. He uses this to argue that our recognition of perfect equality we gained before we were born, which was also taught by Origen, but later condemned as a heresy. Nonetheless it is pretty important in establishing the Realm of Forms, which is interpreted as existing within the mind of God, God the Son (the Logos) specifically. I would recommend reading Plato's dialogues first, and then doing some research into St. Thomas Aquinas. Thomas Aquinas was more of an Aristotelian but his works are pretty foundational in Western Christianity. St. Augustine is also highly important, but I've done less research into his Platonism and more into his teachings on Original Sin.