I'm researching the Armenian genocide on a very basic level, and I've learned that a lot of the tension between Armenians and the Turks was because the Armenians were seen as supporting the Russians, who the Turks hated. Why was there such tension? What did Russia or Turkey do to prove one another?
Turkey and Russia were in each other's way. And Armenia was caught between both of them.
Russia started around Moscow in the late 15th century, and spent the next four or five centuries expanding south. The Turks captured Constantinople in 1453 and spent the next three centuries expanding north.
By the 18th century, Russia occupied Crimea and formerly Turkish held lands on the north shore of the Black Sea. That gave it naval access to modern Bulgaria and Romania, which Turkey considered its sphere of influence. More to the point, Russia's Black Sea holdings were a dagger pointed at the heart of the Turkish heartland, with Armenia being Turkey's "chest." Russia wanted a warm water port, and the primary path would have been through the "Straits." A second means to a warm water port would be through Armenia (which was divided between Russia and Turkey at the time), "Kurdistan" (divided between Turkey, Syria and Iraq), and ultimately Syria, which is why the Russians are involved in Syria to this day.
Armenia (at least in Russian hands) was an existential threat to Turkey, now based in Ankara. Which is why when the Armenians tilted towards Russia, the Turks hated them.
When you do research on the subject, even on a very basic level, you should know that at the time of Armenian genocide, the Ottoman Empire was in the state of WAR with Russian empire. This war is called WWI, or the Great war. And a war can be considered as a maximal possible "tension" between two states.