Persons conversant with virtue say that a disciple is not different from a son. It is for this reason Arjuna is favourite with Drona.
पुत्रादनन्तरं शिष्य इति धर्मविदो विदुः। एतेनापि निमित्तेन प्रियो द्रोणस्य पाण्डवः॥