If you intend on receiving therapy with an individual to target problems you feel are specific to the relationship the two of you have, you should talk to them about the possibility of attending therapy. Your initial consultation is a two way interview though so keep that in mind and know that my treatment plans are developed based on that initial intake interview. This means they'd have to accompany you to that intake interview. Otherwise the therapy is for you and in that case you may invite others as needed to maximize your therapeutic experience
Sure, you can have your friend bring you. I am not, in any way, in charge of your transport to and from therapy. However, when it comes to the therapeutic process, confidentiality and privacy is extremely important so for the traditional 50 minute session, your friend is not allowed unless you are consenting to their presence. Therapy is a private experience, remember that.