Expression: 'I'm Dumbledore's man, through and through'

[lu]

I'm reading harry potter 6. I'm a native spanish speaker. can someone help me understand this expression: 'im Dumbledore's man, THROUGH AND THROUGH'.

i have a good idea, but i would like the real meaning

[Conchita]

'Through and through' means 'completely', 'to the core', 'to the backbone' or, as we say in Spanish, 'to the marrow' (hasta la m?dula) :) !