His first series of books in the mid-1980s, "Once Upon a Soul," "Souled!" and "Soul Survivors", introduced the genre of true, contemporary stories promoting the themes of "hashgacha pratis" (Divine Providence) and human kindness. Teller later branched out into biographies of contemporary Orthodox Jewish personalities — such as Rabbi Shlomo Zalman Auerbach (whose "shiur" he attended for 14 years), Rabbi Levi Yitzchak Horowitz (the Bostoner Rebbe), Baltimore Torah day school principal Rabbi Binyamin Steinberg, Toronto philanthropist Joseph Tanenbaum, and Mir rosh yeshiva Rabbi Nosson Tzvi Finkel (under whom he studied for over 30 years) — using anecdotes to convey moral and ethical lessons. A large section of his corpus presents stories on specific ethical concepts, such as judging others favorably ("Courtrooms of the Mind"), integrity ("Above the Bottom Line"), and avoiding argumentation and strife ("Give Peace a Stance").