Jesus modelled a particular type of relationship – a trainer/trainee relationship. In fact, all of the biblical examples are like that i.e. the mentor is more mature than the disciple. However, there may also be value on peer mentoring so consider that as well.
The Role of Hierarchy in Modern Discipleship – people may balk at the idea of a disciple needing a more mature Christian to disciple him/her. This extract from the book The Whole Life Offering: Christianity as Philanthropy, by Eric Foley explores that.
From Relevant Dude To Spiritual Father. – Kevin A. Miller explores the pastoral role of spiritual fathering/mothering as opposed to leadership and of being a father to young people rather than a peer.