Canto 1 - Boyhood
Bāla-kāṇḍa
Chapter 18: The Advent of Rāma, Lakṣmaṇa, Bharata and Śatrughna
Text 1.18.34

भरतस्यापि शत्रुघ्नो लक्ष्मणावरजो हि सः।
प्राणैः प्रियतरो नित्यं तस्य चासीत्तथा प्रियः॥

bharatasyāpi śatrughno lakṣmaṇāvarajo hi saḥ
prāṇaiḥ
priyataro nityaṁ tasya cāsīt tathā priyaḥ

bharatasya = to Bharata; api = similarly; śatrughnaḥ = Śatrughna; lakṣmaṇa-avarajaḥ hi saḥ = as the younger brother of Lakṣmaṇa; prāṇaiḥ = than His life-airs; priyataraḥ = [was] dearer; nityam = always; tasya ca asīt = and Bharata was also; tathā = similarly; priyaḥ = dear to Śatrughna.

As the younger brother of Lakṣmaṇa, Śatrughna was similarly dearer to Bharata than His life-airs, and Bharata was also similarly dear to Śatrughna.

Bharata and Śatrughna were very attached to each other. That is shown in this verse. Śatrughna was the younger brother of Lakṣmaṇa and so His nature was similar to Lakṣmaṇa’s. Therefore, He was dear to Bharata, and vice versa.