He often describes his time with the Newark PD as a "happy time" of his life as he was still happily married to Rachel and Grace was born.
Danny is portrayed as a loyal cop who is married to his job first and life second.
Danny's "by-the-book" style contrasts with Mc Garrett's "the ends justify the means" approach (which Danny calls "shoot now, ask questions later").
The son of Eddie and Clara Williams, he comes from a large working-class family and is the oldest of four children.
As a consequence, he is often at odds with his ex-wife Rachel for sometimes not being on time to pick up Grace.