Could you give some one herpes simplex 1 if you don't have a cold sore/fever blister?

Maybe. The herpes family of viruses are very common. Some people will get outbreaks, others who are exposed may never have an outbreak, and only with a blood test will find out they were ever exposed. For those who have outbreaks, they can release the virus before a sore is present, either oral or genital sores.