In 2013, Pence signed legislation- House bill 1006 (as governor of Indiana) to make it a felony to lie on an application for a marriage license. The application had space for one man and one woman. Any gay couple applying could have faced 18 months in jail and a $10,000 fine. House bill 1006 also says this: "A person who knowingly solemnizes a marriage of individuals who are prohibited from marrying by IC 31-11-1 commits a Class B misdemeanor."
Granted, I haven't read that anyone was actually charged. But the fact remains, it is there in state law.
He believes homosexuality to be a choice. Believes in conversion therapy
He signed the Religious Freedom Restoration Act in 2015. This would protect any business/corporation from being sued, in choosing to not do business with certain individuals/groups. (After a lot of backlash, it was amended to state something about not allowing discrimination).
Has sought to defund Planned Parenthood since (at least) 2011. It even earned the name, "The Pence Amendment."
In March 2016, signed into law outlawing abortions if the fetus has an abnormality. Also requiring the remains of an aborted or miscarried fetus be interred or cremated. (There is an injunction preventing the law from taking effect as of now). The law also restricts fetal tissue donation.
I also see him as the primary person in charge. One article I read wrote, "he could be the most powerful vice president ever." He is also leading Trump's "transition team."